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nRD24-02 - SemiconductorStore.com

1. 8 agy 8 es an 989 B as a8 E SE E E 2s eg ei EE S SEST a BRAR a s E S a se R VAS o os S EgG a I Ova e a He B d B 8 T 5 E Te GES 8 I st HESS G e ms P ee obs 2 a S Og Es 9 5 H T0 wos amp e Ea m 2S O 9 2 os som SES 4 BRS Bae Oo m a lt A 25 o on a SCH as a E a se gs r A PII a SE alg ala I aH ke 5 1 ch IL zi S ra S BS N SA SA HH qe On A fd aana er S zli ADN Hi i a Him S oaas Her RE T en sm LU S6 ge NMdleloadu mz qo or EI SPPE li SEE 5 83 b s d JA E BEETJE s S o Hi Ss d S Ih a B E z T SE Se ae A E if f H S 2 s 2 E iA ext E 2 os Q A E a 3 FE 8 te o ER H os a J4 a Ba 1 ER a i I 3 eX a gp s s S Figure 5 7 ARX Board RF Core Nordic Semiconductor ASA Vestre Rosten 81 N 7075 Tiller Norway Phone 47 72 898900 Fax 47 72 89 89 89 Revision 1 0 Page 48 of 59 Date January 2006 REFERENCE DESIGN nRF24Z1 Headphone Reference Design 1 nRF24Z1 HPR1 VDDD VDDD Nordic Semiconductor ASA Revision 1 0 20 IW
2. i Inductance vs freguency may differ significantly in inductors with the same value but different part numbers and or vendors Inductor value is usually characterized at 100 250 MHZ but the actual value at 2 4 GHz may vary significantly even though the given inductance at 250 MHZ is the same Inductors from other TOKO series and other vendors may well be used but antenna matching network performance MUST be verified as the inductor value may need to be changed Nordic Semiconductor ASA Vestre Rosten 81 N 7075 Tiller Norway Phone 47 72 898900 Fax 47 72 89 89 89 Revision 1 0 Page 46 of 59 Date January 2006 REFERENCE DESIGN nRF24Z1 Headphone Reference Design 1 nRF24Z1 HPR1 Designator Description Footprint Wolfson Microelectronics WM8951LGEFL QFN5x5 28 Stereo ADC with Microphone Input and Clock Generator Atmel ATmega48V 10MI 8 bit AVR QFN5x5 32 Microcontroller with 8K Bytes Flash Crystal C 9pF C lt 7pF ESR lt 1000 SMD Frequency tolerance temperature stabillity 30 ppm Table 5 1 ATX BoM Nordic Semiconductor ASA Vestre Rosten 81 N 7075 Tiller Norway Phone 47 72 898900 Fax 47 72 89 89 89 Revision 1 0 Page 47 of 59 Date January 2006 REFERENCE DESIGN nRF24Z1 Headphone Reference Design 1 nRF24Z1 HPR1 5 2 ARX Board 5 2 1 Schematics Figure 5 7 to Figure 5 10 shows the ARX board schematics El Fractus FRO5 S1 N 0 102
3. A detected Sat A No x WAKE WAH lt 1 Sad ate Co ATX is wake on timer Insert audio source off indio m TS Yes ATX nRF24Z1 SU Muse sequence interface N active g d L period elapsed Yes x HC EE AX Power down ADC Set new private address No Ps kom No 1 Y lt lt Linkfound 7 A 4 C ET S u powermode Weitforlnkup w Yes PMODE_AUTODOWN Button pressed on Y N No ARX P Y di no CD SSC J Se 2 E Ra i S kouna Yes Button pressed on No lc EMI ART Consider ATX buttons Y Yes No Insert audio source on Ka x sequence Yes y Power on remote DAC Y Consider ARX buttons Consider ARX buttons X User puts Ps E No system to P a Wake up ADC deep lt DAC success gt y mode powermode o A PMODE_AWAKE Button pressed on ke Stop pressed ATX Yes Y v V Power down DAC e Yes Y Yes x denger Insert audio source off Power down ARX Consider ATX buttons User brings GC seguence Y system out of pressed sleep mode Power down ATX E Yes Power down DAC v x powermode lt Play pressed gt Increase volume v PMODE POWERDOW E No Power down ARX N v A RS p Power down ATX eU x NG Y Volume down gt died up Power down ADC Ss 7 ES d v SoU Insert audio source on Ze T Disable ATX auto power sequence Yes Bike EOWERDOWR down x S Decrease volume y Ge d Alter TXMOD for power Wake up ADC up e Y y Wake up DAC Pa Kom a Alter RXMOD to attempt e 1 Other button power up gt MCU p
4. e hpref defines h Top level definitions for the entire MCU source code All preprocessor define statements should be put in this file unless they are hardware dependant or better understood in the context where they are used e main c Top level container for linkup and user interface This file includes the code that receives and decodes interaction with the user power down modes and pairing e main _optionX c Power down modes user interface main program X 1 2 or 3 e zislaveio h and zlslaveio c Communication between the MCU and the nRF24Z1 chips Functions defined in z1slaveio h provide low level and mid level read and write operations e uartdebug h and uartdebug c Debug information to be used while developing the MCU source code Functions declared in uartdebug h are not used in code compiled for production versions of the product e adc h Declaration of functions that all ADCs must support This file is hardware independent Nordic Semiconductor ASA Vestre Rosten 81 N 7075 Tiller Norway Phone 47 72 898900 Fax 47 72 89 89 89 Revision 1 0 Page 27 of 59 Date January 2006 REFERENCE DESIGN nRF24Z1 Headphone Reference Design 1 nRF24Z1 HPR1 e adc wm8951 c Hardware dependent implementation of the functions declared in adc h This file is written for the Wolfson WM8951L ADC It and not adc h must be ported 1f you choose to design with a different ADC e dac h Declaration of functions that all DACs must suppor
5. REFERENCE DESIGN nRF24Z1 Headphone Reference Design 1 nRF24Z1 HPR1 6 Daughterboard 6 1 Daughterboard Schematic Figure 6 1 shows the Daughterboard circuit schematic D Connector 9 C1001 luF 1 MAX3218CAP s m A A a QE S EB sm mu A8 Sg EE li Q mg 2 S amp EEGEN o S EE O amsoocrveasz5x5 E a e a e oeeo oo oeo oo li fu x SL M M 57 1 dadd e E E x x a a zv a m S EE cc z B B eB AS o DS of SEELEN Sg a ao eil SR a gt Figure 6 1 Daughterboard schematic Nordic Semiconductor ASA Vestre Rosten 81 N 7075 Tiller Norway Phone 47 72898900 Fax 47 72 89 89 89 Revision 1 0 Page 54 of 59 Date January 2006 REFERENCE DESIGN nRF24Z1 Headphone Reference Design 1 nRF24Z1 HPR1 6 2 Daughterboard Bill of Materials Designator Description Footprint Capacitor Tantalum 2096 20V 1206 Capacitor Tantalum 2096 20V 1206 Capacitor Tantalum 2096 20V 1206 Capacitor Tantalum 2096 20V 1206 Capacitor Tantalum 2096 20V 1206 Switch mode inductor saturation current gt 350mA resistance lt 1 ohm 1812 Silicon diode Philips PMBD6050 SOT 23 Female D SUB 9 pin
6. 10 16V Capacitor Tantalum 20 6V ESR lt 3Q Capacitor X7R 10 16V Capacitor X7R 10 16V Capacitor X7R 10 16V Capacitor Tantalum 20 6V ESR lt 3Q Capacitor Electrolytic 20 10V Capacitor Electrolytic 20 10V Capacitor NPO 5 50V Capacitor NPO 5 50V Chip inductor 0 3nH TOKO LL1608 FSL3N3S Chip Inductor 596 Chip inductor 0 3nH TOKO LL1608 FSL3N3S i Inductance vs freguency may differ significantly in inductors with the same value but different part numbers and or vendors Inductor value is usually characterized at 100 250 MHZ but the actual value at 2 4 GHz may vary significantly even though the given inductance at 250 MHZ is the same Inductors from other TOKO series and other vendors may well be used but antenna matching network performance MUST be verified as the inductor value may need to be changed Nordic Semiconductor ASA Vestre Rosten 81 N 7075 Tiller Norway Phone 47 72 898900 Fax 47 72 89 89 89 Revision 1 0 Page 52 of 59 Date January 2006 REFERENCE DESIGN nRF24Z1 Headphone Reference Design 1 nRF24Z1 HPR1 Designator Description Footprint LED red 1206 Philips Discrete Double Diode BAW56 SOT 23 Philips Discrete Double Diode BAW56 SOT 23 Antenna Fractus FRO5 S1 N 0 102 SMD Audio telejack 3 5
7. HardWare System desigi E 6 3 1 ATX Eege ees 6 32 ARX RE 6 3 3 Power supply and current consumption ssssssssesseeeeeee eren 7 3 4 Power supply noise and audio quality consderattong sess 7 3 5 E 8 3 6 eenegen 10 ET 12 4 1 Look and Feels T pe A E R RRE E E 12 4 2 Pairing establishing a private address seessssseeeeeeeenene 14 43 User Interface Buttons and LED eegene ed Hec EUN D E 16 4 4 Sleep Modes m eebe Eeer E E EERE 17 4 4 1 Automatic Power LIOQTLauuseedursud unis anreisen iine adut Dess uM cab uM EEEE 18 4 4 2 KE e EE 18 4 4 3 KE E C 19 4 4 4 Interrupting MCU when Waking up sis snisesstincasensscvetasnesutsonsilarssindseNassenasiasanes 19 4 4 5 Audio Streaming Mode gege een 19 4 4 6 Wakeup from Automatic Power Down 19 COMME unacum 20 4 5 1 Full UI on ATX User Interface Option 1 20 4 5 2 Full UI on ARX User Interface Option 21 21 4 5 3 Full UI on ARX and ATX User Interface Option 21 23 4 5 4 Identifying Sleep Modes in MCU Source Code 24 46 ee ei E Q 27 4 6 1 Definitionsin Ge Ee Eegenen 28 4 6 2 Implementations in main c and included Dies 30 4 6 3 Implementations in zlslaveio hand zlaslaveio e 20 4 6 4 Implementations in uartdebug h and uartdebug e 32 4 6 5 Implementations in adc h and ado wmpg99 sssasaecseedcstensancdeonenteneenssionss 33 4 6 6 Implementations in dac h and dac wma711 e iius ens 33 4 6 7 Implementations in mcu
8. N 7075 Tiller Norway Phone 47 72 89 89 00 Fax 47 72 89 89 89 E mail nRF nordicsemi no Visit the Nordic Semiconductor ASA website at http www nordicsemi no v 03 NS EN ISO 9001 CERTIFICATEDEIRM Nordic Semiconductor ASA Vestre Rosten 81 N 7075 Tiller Norway Phone 47 72898900 Fax 47 72 89 89 89 Revision 1 0 Page 59 of 59 Date January 2006
9. Nis Play on Y ATX for Y Wake ATX nRF24Z1 pes w ao with interrupt from MCU exitloop P Y PMODE_AUTODOWN lt dp MM Alter TXMOD for power ne up NI PMODE_POWERDOWN Waitforlnkup y User Play pressed on No MCU Reech SE WAKE_WAIT WAKE Z1 INT WAKE Z1 INT WAKE WAIT Link found automatic Yes sleep N x mode pd Wake ATXnRF24Z1 L Not supposed to receive Not supposed to receive No with interrupt from MCU interrupts from ATX interruptts from ATX x Play pressed on KE KE ATXNRF2AZI ag Put ATX nRF24Z1 back X Y Y 3 to wake on interrupt Wait for linkup J 1 p ba LY Va No y Pale E Wait to poll again ye Be bi Yes S MUKE Button pressed ori 4 ARX nu Run user ps No Wake ATX nRF24Z1 Insert audio source off interface Poli LS with interrupt from MCU sequence No A Ready to receive i37 Y Automatic SG S r Consider ATX buttons private address Yes Pisala ATauiconar power n P Polet do ADG down Yes jown ower down PE L y Yes Insert audio source on Y Y x sequence Alter TXMOD for power mem E Consider ARX buttons Set new private address No up PMODE AUTODOWN User puts system y Y Y into sleep Waitforlinkup Wake up ADC Alter RXMOD to attempt mode power up 1 a y v e NU No Stop pressed m is powermode Wait for linkup P lt Link found Sey i re Sei JI Y system Yes 1 out of Insert audio source off D sleep Volume up Yes sequence E mode pressed Power on remote DAC No x
10. Rev 1 0 Nordic Semiconductor ASA Nemko Comlab AS Test Report 57841 5 Tests according to FCC CFR 47 Part 15 247 and Industry Canada RSS 210 Issue 6 Nemko Comlab AS Test Report 57841 6 Tests according to ETSI EN300 Datasheet WM8711 WMS711L Internet Audio DAC with Integrated Headphone Amplifier Rev 4 2 Wolfson microelectronics Datasheet WM8951L Stereo ADC with Microphone Input and Clock Generator Rev 4 0 Wolfson microelectronics Application Note WAN 0129 Decoupling and Layout Methodology for Wolfson DACs ADCs and CODECs Rev 1 0 Wolfson microelectronics Application Note AN 0144 Using Wolfson Audio DACs and CODECs with Noisy Supplies Rev 1 3 Wolfson microelectronics Datasheet Compact Reach Xtend Chip Antenna FR05 S1 N 0 102 Ref DS_FRO05 S1 N 0 102_v01 Fractus User Manual Compact Reach Xtend Chip Antenna FR05 S1 N 0 102 Ref UM_FRO5 S1 N 0 102 September 2005 Fractus Application Note Compact Reach Xtend Chip Antenna FRO5 S1 N 0 102 Ref AN FR05 S1 N 0 102 January 2005 Fractus Nordic Semiconductor ASA Vestre Rosten 81 N 7075 Tiller Norway Phone 47 72 898900 Fax 47 72 89 89 89 Revision 1 0 Page 56 of 59 Date January 2006 REFERENCE DESIGN nRF24Z1 Headphone Reference Design 1 nRF24Z1 HPR1 LIABILITY DISCLAIMER Nordic Semiconductor ASA reserves the right to make changes without further notice to the product to improve reliability functio
11. 2 wire write command that writes data to the internal address adr of the device with hardware device address devadr e void mcu uart init void Initializes the debug UART This function requires DEBUG to be defined It sets the debug baud rate e int mcu putchar char c Writes a single character c to the UART c may be a letter CAT n or a hex number This function requires DEBUG to be defined e int mcu getchar void Waits for a single character to arrive on the UART This character is then returned by the function This function requires DEBUG to be defined e char mcu buttons void This function reads the MCU IO pins associated with the ATX user interface It then returns a button code from the table in hpref_defines h The button code is chosen to be egual to how the ARX buttons are reported in RXPIN e void mcu atxled char mode Turns the ATX LED on node LEDON oroff mode LEDOFF This function requires USELED to be defined e void mcu zlint clear void Resets the internal interrupts in the ATX nRF24Z1 Please note that when using this function the nRF24Z1 must be powered on and not going to sleep mode for the required write accesses to be completed This function requires Z1 INTERRUPT to be defined e void mcu zlint enable void Lets the MCU be interrupted by the interrupt output IRQ pin of the ATX nRF24Z1 This function requires Z1 INTERRUPT to be defined e void mcu zlint disable void Disables the ATX
12. Headphone Reference Design This dynamic pairing happening every time the units are turned on may be a feature in some applications product family sharing an audio source with multiple headphones and HiFi systems and a problem in others static systems There are three other ways to perform pairing e Produce the ATX and ARX EEPROMs with equal and unique 40 bit addresses This will demand more from production and logistics Also if for example the ATX fails the ARX is useless to the consumer e Produce all units with equal EEPROMs and perform pairing as the last stage of production or as the first stage after the user powers the system on the first time After this the units will stay paired every time they are turned on Without dynamic pairing units with this kind of pairing render both ATX and ARX useless if one of them fails This requires that the private address generated during pairing is programmed into the EEPROM of the ARX Information on how this is implemented is available from Nordic Semiconductor support e User intervention to choose address Dip switches or digital selector wheels may be used to select among a small selection of addresses A microcontroller would be needed to read the digital code and write it into the nRF24Z1 through its slave interface The Headphone Reference Design uses dynamic pairing at every power up So if you select Battery OFF on one device you must also select Battery OFF on the other one in ord
13. LEDs and converters that need setup sequences The nRF24Z1 evaluation board and the STK500 have active low buttons and LEDs combined with intant on audio converters Another important difference is that the nRF24Z1 on the ATX evaluation board is DS slave while it is DS master on the Headphone Reference Design This must be set in the EEPROM define ATXDEVBOARD ATX is development board not finished product define ARXDEVBOARD ARX is development board not finished product The Headphone Reference Design uses the 2 wire slave interface of the ATX nRF24Z1 When 2 wire is selected certain other parameters may be defined as well define Z12WDEVADR 0500101001 Either nRF24Z1 slave dev adr SADR 0 define Z12WDEVADR 0501101001 Or nRF24Z21 slave dev adr SADR 1 define TERMINATE ON ERROR Halt program at unexpected stat The Headphone Reference Design has a built in debugging system Selecting to compile it in will increase your compiled image size while offering you more control over your application development There are multiple levels of debugging which may be turned on and off at compile time Nordic Semiconductor ASA Vestre Rosten 81 N 7075 Tiller Norway Phone 47 72 898900 Fax 47 72 89 89 89 Revision 1 0 Page 28 of 59 Date January 2006 REFERENCE DESIGN nRF24Z1 Headphone Reference Design 1 nRF24Z1 HPR1 define DEBUG Enable debug information to ter
14. Link found User Volume up down prev next song etc Link found User Play Link lost m rut P EE S Receive Powerdown Autodown ATX commands WR len eebe See User Stop User Play User Play User Stop User Volume up down prev next song etc Figure 4 1 Pairing user interface options 1 and 2 Nordic Semiconductor ASA Vestre Rosten 81 N 7075 Tiller Norway Phone 47 72898900 Fax 47 72 89 89 89 Revision 1 0 Page 15 of 59 Date January 2006 REFERENCE DESIGN nRF24Z1 Headphone Reference Design 1 nRF24Z1 HPR1 ATX Insert batteries User ON Establish private address User Volume up down prev next song etc ARX Insert batteries User ON Receive new private address Link found Link found User Play Link lost p EQ S LEE ag Receive Powerdown Autodown ATX commands WR len Nile cnin tuu Link found User Stop User Play User Volume up down prev next song etc User Stop Figure 4 2 Pairing user interface option 3 4 3 User Interface Buttons and LED In the Headphone Reference Design 12 different buttons common in audio equipment have been identified and supported in the MCU source code These are Play Volume up Volume down Stop Skip forwards Skip backwards Scan forwards Scan backwards Bass boost Reconnect radio Power and Mute Of these the following have been implemented on the ATX and ARX PCBs e Volume up when presse
15. Revision 1 0 Page 45 of 59 Date January 2006 REFERENCE DESIGN nRF24Z1 Headphone Reference Design 1 nRF24Z1 HPR1 Designator Description Footprint Audio telejack 3 5mm stereo Axial Chip inductor 0 3nH TOKO LL1608 FSL3N3S 0603 Chip Inductor 596 0603 Chip inductor 0 3nH TOKO LL1608 FSL3N3S 0603 Connector Molex 54167 0208 SMD Resistor 10 0603 Resistor 1 0603 Resistor 5 0603 Resistor 5 0603 Resistor 5 0603 Resistor 0603 Resistor 0603 Resistor 0603 Resistor 1 0603 Resistor 1 96 0603 Resistor 596 0603 Resistor 596 0603 Resistor 596 0603 Resistor 596 0603 Resistor 596 0603 Resistor 596 0603 Resistor 5 0603 Resistor 5 0603 Resistor 5 0603 Resistor 5 0603 Resistor 5 0603 Resistor 5 0603 Resistor 5 0603 Resistor 5 0603 Power supply on off switch Axial User interface push button ALPS SKQMBBE010 SMD User interface push button ALPS SKQMBBEO0IO SMD User interface push button ALPS SKQMBBE010 SMD U U ser interface push button ALPS SKOMBBEO010 SMD ser interface push button ALPS SKOMBBEO010 SMD User interface push button ALPS SKQMBBE010 SMD nRF24Z1 2 4GHz Transceiver for Audio Streaming QFN36L 6x6 EEPROM Microchip 25AA640 I SN 64K 1 8V SPI Bus Serial EEPROM SO 8 Voltage Linear Technology LT1761ES5 BYP 100mA regulator Low Noise LDO SOT 23
16. Therefore all buttons except Volume Up and Down will not affect the audio However the MCU source code identifies insertion codes for audio source control seguences The Headphone Reference Design does not feature a control link to the audio source Therefore the music source must be activated manually After the Play button has been pressed and held to activate the ATX and ARX subseguent use of the Play button will have Pause functionality When the audio is paused the radio link is still active and no power save takes place Pressing Play again will make the audio come back Like a CD player Play Pause have a shorter response time and higher power consumption than do Play Stop The Stop button will put the ATX and ARX in sleep mode and cut off the music The Volume Up and Down buttons will increase or decrease the audio level These buttons may be held for continuous increase or decrease in audio level The Next Previous Song buttons do not produce any result visible to the user But the buttons are decoded in the MCU source code and may be used to control the audio source in an integrated product All buttons may be redefined in software Every action that may need to control the audio source has been identified in comments in the MCU source code This may be turning on or pausing the audio when Play is pressed stopping it when Stop is pressed moving forwards or backwards in the music etc 4 2 Pairing establishing a private address
17. adc wm8951 c Your choice of ADC may vary from the one chosen for the Headphone Reference Design There adc wm8951 c implements hardware dependant control sequences for the Wolfson WMS951L chip If you change the ADC you will have to make your own adc zzzz c file for hardware dependant control sequences However you should not have to rewrite adc h which is made to hold general purpose definitions of ADC functions e void adc init void Initializes the ADC This function will typically set up sampling frequency and IO It is therefore different from the functions that bring the ADC in and out of power down However for the Wolfson WM8951L entering sleep mode requires a chip reset Thus the init and wakeup functions are the same e void adc sleep void Puts the ADC into power save mode e void adc wake void Wakes up the ADC from power save mode e void adc singlewrite char adr char data Write a single data word data to a certain ADC internal address adr Most ADCs have write only control interfaces This function is used internally by the other ADC functions and directly from the interactive debugging interface Beware that most Wolfson chips use 7 bit address and 9 bit data Thus the seven most significant bits of adr will contain the internal address while the least significant bit of adr and all of data will contain the nine bits of information to be written 4 6 6 Implementations in dac h and dac wm8711 c Your choice of DA
18. and after having lost its link for the specified time the devices will enter the sleep modes set by TXMOD RXMOD RXWAKE TXWTI TXSTI TXLTI RXWTI RXSTI and RXLTI These registers may very well be set only once in the EEPROM They do not all need to be set by the MCU source code The next two sections will describe the two available sleep modes 4 4 Wake on Interrupt The nRF24Z1 may be programmed to stay in a low power sleep mode until one or more of its input pins change polarity This is the sleep mode with the lowest current consumption For the ARX the interrupt source may be any combination of four general purpose input pins In the Headphone Reference Design the input pin corresponding to the Play button is set as the only interrupt source General purpose input pins are available when the Slave Interface SPI or 2 wire connection to MCU is disabled on the ARX For the ATX only one input pin DD 1 is available as an interrupt source On the Headphone Reference Design this pin is an output from the MCU That way the MCU may poll or be interrupted by the user interface buttons on its own input pins and then consider whether or not to interrupt and wake up the ATX If the right button is pressed the MCU may interrupt the nRF24Z1 to wake it up This is beneficial as the MCU is better suited than a user at maintaining DD 1 hold time Please note that both positive and negative edges on the selected input pins will trigger interrupts
19. automatic power down requires user interaction on the ATX A typical application example is a wireless headphone with limited user interface Today s wired headphones rarely have user interfaces on them Figure 4 3 shows a flowchart of this user interface option Nordic Semiconductor ASA Vestre Rosten 81 N 7075 Tiller Norway Phone 47 72898900 Fax 47 72 89 89 89 Revision 1 0 Page 20 of 59 Date January 2006 REFERENCE DESIGN nRF24Z1 Headphone Reference Design 1 nRF24Z1 HPR1 p N f AEN is on auto power down after ME Jj searching for a link for 500ms It then p ATX goes straight to power down with g d searches for a link for 10ms and sleeps wake on interrupt TXMOD must be o y altered for initialATX poweron eg eer a inis d ieee J Power down ADC KN P NN not be changed for initial SEH power on X E 4 Play pressed on LI MCU r Y TE Wait for ATX interrupt e H MCU timeout
20. e LNKMOD 0x08 Mute when LNKERR gt LNKETH e NLCH 0x0F Nordic Semiconductor ASA Vestre Rosten 81 N 7075 Tiller Norway Phone 47 72 898900 Fax 47 72 89 89 89 Revision 1 0 Page 37 of 59 Date January 2006 REFERENCE DESIGN nRF24Z1 Headphone Reference Design 1 nRF24Z1 HPR1 e ADDR use your preferred initial address This address must match that of function zl setinitialadr Interrupts tab in zlconfig e INTCF 0x02 Enable wakeup from power down interrupt Transmitter tab in zl config e I2SCNF_IN 0x80 Audio mode Master mode TXLAT 0x04 Nominal 20ms 48kHz TXWTI 0x02 TXLTI 0x4A TXSTI 0x0030 TXMOD 0x82 RF DS 44 1 Receiver tab in zlconfig e RXSTA 0x40 Disable serial slave interface e RXWTI 0x02 RXLTI 0x4A RXSTI 0x0000 RXWAKE 0x02 Wakeup on DI 1 change I2SCNF OUT 0x40 Mute sound RXMOD 0xA0 RF DS RX power down 4 8 3 Full User Interface on ATX and ARX User Interface Option 3 With this setup any ATX or ARX unit will try to establish a link for a short time before going to a wake on timer sleep mode When one ATX and one ARX are turned on and within range of each other the MCU will power them on relink them on a private address and make them enter sleep mode both are wake on timer before starting the user interface The user must then press and hold the Play button in order to bring the units out of sleep mode This way a unit is only operating on its initial address until its counterpart is turned on with
21. in AVRstudio If asked to select the PC RS232 port where the cable was just connected Go to the Board tab in the new window Set the voltages to 3 0V Select Write Voltages No connection exists between VTG or VDD on the STK500 and the Nordic boards and all signals between STK500 and the boards are protected with series resistors on the Daughterboard Still voltages must be set in order to make the logic levels compatible When this is done power off the STK500 and connect a 6 pin ribbon cable between the header on the Daughterboard and the ISP6PIN header on the STK500 Mind the location of pin 1 It is only marked as a square pad on the Daughterboard Connect the Daughterboard to the ATX and then power it on In the STK500 window go to the Program tab Select Device Atmega48 and Programming mode ISP Also select Erase Device and Verify Device Under Flash browse to the attached main hex file Click Program This should update the MCU flash The editor used in this project is called Programmers Notepad It comes with the WinAVR software package Once WinAVR is installed a link to Programmers Notepad should appear on your desktop After starting Programmers Notepad open the relevant c and h files To compile the Headphone Reference Design MCU code select Make All from the Tools menu This will generate the main hex file described above 4 8 Setup of EEPROM and zlconfig You may use zlconfig to change the defau
22. in RXMOD and RXWAKE 4 4 4 Interrupting MCU when Waking up The nRF24Z 1 has several ways of interrupting an external MCU or other electronics The Headphone Reference Design only uses one interrupt and it only uses it on the ATX The wakeup from power down interrupt is the only interrupt whose interrupt flag does not have to be cleared in INTSTA Enabling the wakeup from power down interrupt on the ATX makes the nRF24Z1 IRQ output pin track the sleep modes of the nRF2421 An active low IRQ pin will be low when the ATX nRF24Z 1 is streaming audio or trying to establish a link It will be high when the ATX nRF24Z1 is waiting between attempts at establishing a link Through being interrupted by this pin or polling it the MCU will know when the SPI or 2 wire slave control interface of the nRF24Z1 may be accessed This also means that if the ATX is Wake on Timer the external MCU does not have to be in charge of system timing while in sleep mode Instead the MCU is interrupted by the ATX nRF24Z1 whenever it wakes up and becomes ready to receive commands However since the nRF24Z1 units may also wake up from automatic power down or for some other reason cease generating interrupts it is important that the MCU has a backup clock that makes sure the system does not hang if an expected interrupt should not occur 4 4 5 Audio Streaming Mode This is the normal operation of the system audio content is streamed from the ATX to the ARX While in Audio S
23. interrupt Nordic Semiconductor ASA Vestre Rosten 81 N 7075 Tiller Norway Phone 47 72 898900 Fax 47 72 89 89 89 Revision 1 0 Page 31 of 59 Date January 2006 REFERENCE DESIGN nRF24Z1 Headphone Reference Design 1 nRF24Z1 HPR1 definitions are featured in hpref defines h You must define Z1 INTERRUPT to use this function e void zl intinit char interrupts This function is used to initiate the nRF24Z1 interrupts The parameter is an OR mg together of the definitions of the interrupts to be used for example zl intinit INT LBROKEN INT LQUAL to receive interrupts if the link is broken or if the link guality falls below the threshold You must define ZLINTERRUPT to use this function e void zl intdeactivate void Disables all nRF24Z1 interrupts You must define Z1 INTERRUPT to use this function More interrupt functions are found in the MCU dependant code below 4 6 4 Implementations in uartdebug h and uartdebug c The debugging subsystem is not required in production versions of your product It is only compiled when DEBUG is defined However it has been included to aid developing a final products and reprogramming the Headphone Reference Design The debugging subsystem uses an UART to communicate with the RS232 interface of a PC The baud rates are listed in the function meu uart init The debugging subsystem is based on meu putchar and mcu getchar in the MCU dependant code If you need to identify
24. nRF24Z 1 interrupt output pin IRQ pin from affecting the MCU This function requires Z1 INTERRUPT to be defined e char mcu zlint active void This function is used to see if the ATX nRF24Z 1 is currently awake and able to receive commands on its slave interface It returns 1 if the ATX nRF24Z I is active and 0 if it is inactive The function requires the Wakeup from power down interrupt to be enabled in the nRF24Z1 configuration EEPROM e void mcu zlwakeup pin void Sends a wakeup pulse to the ATX nRF24Z1 wakeup pin DD 1 The MCU is able to hold this signal for the specified hold time In user interface option 1 the Headphone Reference Design polls the ATX Play button attached to the MCU and then calls this function when the button is pressed Nordic Semiconductor ASA Vestre Rosten 81 N 7075 Tiller Norway Phone 47 72898900 Fax 47 72 89 89 89 Revision 1 0 Page 35 of 59 Date January 2006 REFERENCE DESIGN nRF24Z1 Headphone Reference Design 1 nRF24Z1 HPR1 4 7 Setup of AVR Studio STK500 and WinAVR Two support tools from Atmel are required if you want to modify and update the compiled microcontroller code residing on the ATX board Download AVRstudio from http www atmel com dyn products tools_card asp tool_id 2725 Install the program Connect a RS232 cable between your PC and the RS232 CTRL header on the STK500 board Power on the STK500 board with no connection to the Nordic board yet Click on the AVR tab
25. void mcu wait ms unsigned int time Waits the specified number of ms Any multiple of 32ms wait is performed by means of the watchdog interrupt The function will wait until the specified time has passed or until an interrupt occurs The function is employed for general purpose waiting and as a safety timer that strikes an alarm if an expected interrupt does not occur The wait time is terminated by the passing of t ime ms or by an arriving enabled interrupt char mcu randombyte void Returns a random byte In the Headphones Reference Design the randomness is based on the assumption that the MCU clock is asynchronous from the 12S bit clock The bit clock is used as an input to a linear shift feedback register void mcu 2w master init void Sets up the MCU s hardware 2 wire master interface that is used to access ATX nRF24Z internal registers char mcu 2w read char devadr char adr General purpose 2 wire read command that returns the data found in internal address Nordic Semiconductor ASA Vestre Rosten 81 N 7075 Tiller Norway Phone 47 72 898900 Fax 47 72 89 89 89 Revision 1 0 Page 34 of 59 Date January 2006 REFERENCE DESIGN nRF24Z1 Headphone Reference Design 1 nRF24Z1 HPR1 adr ofa device answering to hardware device address devadr This function is used both for the nRF24Z1 and the ATX ADC Their hardware addresses are defined in the calling code e void mcu 2w write char devadr char adr char data General purpose
26. 006 REFERENCE DESIGN nRF24Z1 Headphone Reference Design 1 nRF24Z1 HPR1 and programming It also holds a RS232 level converter IC An important thing to notice is that the Daughterboard may not be used to read and write internal nRF24Z registers like zlconfig in conjunction with the nRF24Z1 Evaluation Boards It only supports the EEPROM features found under the EEPROG tab in zl1config The Daughterboard consists of a printed circuit board PCB with RS232 and programming headers For connection between the Daughterboard Molex 52435 3072 connector P1003 and the ATX ARX board Molex 54167 0208 connector P501 a FFC Flat Flexible Cable soldered to a small PCB with a Molex 53916 0208 connector P1 has been made The FFC shall be inserted into the Daughterboard P1003 connector and the P1 connector shall connect to the ARX ATX board P501 connector When properly attached the FFC points outwards from the ARX and ATX boards See the picture in Figure 3 3 below D Awi 2896 BOC Vw I oc wi E AXON CABLE Figure 3 3 Daughterboard connection to ARX ATX board The Daughterboard circuit schematic and Bill of Materials can be found in chapter 6 Schematic for the small PCB with the Molex 53916 0208 connector P1 can also be found in chapter 6 Nordic Semiconductor ASA Vestre Rosten 81 N 7075 Tiller Norway Phone 47 72898900 Fax 47 72 89 89 89 Revision 1 0 Page 11 of 59 Date January 2006 REFERENCE DESIGN nRF24Z1 Headp
27. 305 C304 C303 0 1ux C302 0 luF C301 10uF VDD_D C314 0 1uF R302 10K R301 10K VDDD VDDD Nordic Semiconductor ASA Revision 1 0 pee Figure 5 2 ATX Board Audio Front End with ADC Vestre Rosten 81 N 7075 Tiller Norway Page 41 of 59 Phone 47 72 89 89 00 Fax 47 72 89 89 89 Date January 2006 REFERENCE DESIGN nRF24Z1 Headphone Reference Design 1 nRF24Z1 HPR1 S e A 83 S Za T a M ee Na E os zb Sp a 38 3 E d T al e e e 25 al o a a E c FE a o S m Je Su HI 3 ic gx a I g lt 7 JC Do Pog 8 x amp 5 A 2 o 5b E E o E o E Figure 5 3 ATX Board MCU and user interface push buttons Nordic Semiconductor ASA Vestre Rosten 81 N 7075 Tiller Norway Phone 47 72898900 Fax 47 72 89 89 89 Revision 1 0 Page 42 of 59 Date January 2006 REFERENCE DESIGN nRF24Z1 Headphone Reference Design 1 nRF24Z1 HPR1 VDD nRF nRF24Z1 supply VDD A ADC DAC analogue s
28. ARX and ATX boards current consumption 3 4 Power supply noise and audio quality considerations Like in all electronic design the quality of the design is not only decided by the active devices themselves but also how they work together Basically there are two very important things to look out for in a nRF24Z design e Noise crosstalk through the power supply e Ground layout The nRF24Z 1 is a two way package based radio meaning it will constantly switch between transmit receive transmit receive and so on In these two modes the current drawn will be different which may give rise to voltage ripple on the power supply If this voltage ripple is allowed to enter the analogue audio part of the design ADC DAC CODEC a constant 250 430Hz tone might be present in the loudspeakers Nordic Semiconductor ASA Vestre Rosten 81 N 7075 Tiller Norway Phone 47 72898900 Fax 47 72 89 89 89 Revision 1 0 Page 7 of 59 Date January 2006 REFERENCE DESIGN nRF24Z1 Headphone Reference Design 1 nRF24Z1 HPR1 Hence when nRF24Z 1 is used in combination with ADC DAC CODECs the nRF24Z1 must be considered to belong to the digital domain Because of this it is very important to avoid power supply noise generated by nRF24Z1 and other digital circuitry from reaching the analogue supply pins and reference voltage pins of the ADC DAC CODEC Star routing directly from a low noise supply source e g a linear voltage regulator is highly recommended The
29. C may vary from the one chosen for the Headphone Reference Design There adc wm8711 c implements hardware dependant control sequences for the Wolfson WMS711L chip If you change the DAC you will have to make your own dac yyyy c file for hardware dependant control sequences However you should not have to rewrite dac h which is made to hold general purpose definitions of DAC functions Accessing the ARX DAC from the ATX MCU employs the auxiliary data channel of the nRF24Z1 The functions used for DAC access may therefore be useful if you plan to remote control various ARX hardware from the ATX e char dac init void Initializes the DAC This function will typically set up sampling frequency IO and initial audio volume It is therefore different from the functions that bring the DAC in and out of power down The function returns OKAY or TIMEOUT depending on the state of RXEXEC that governs this part of the auxiliary data channel e char dac volume up void Increases ARX volume Returns RXEXEC state Nordic Semiconductor ASA Vestre Rosten 81 N 7075 Tiller Norway Phone 47 72 898900 Fax 47 72 89 89 89 Revision 1 0 Page 33 of 59 Date January 2006 REFERENCE DESIGN nRF24Z1 Headphone Reference Design 1 nRF24Z1 HPR1 4 6 7 char dac volume down void Increases ARX volume Returns RXEXEC state char dac bass boost void The WM8711L does not feature any bass boost However this function is supported in the general purpose dac
30. MODE AWAKE WAKE Z1 INT System is streaming audio but an interrupt is received This indicates that the ATX nRF24Z1 went to Wait on Timer sleep mode Le the ATX went to automatic power down The MCU subsequently puts into sleep mode the units it can reach ADC and itself It then sets powermode PMODE AUTODOWN PMODE AWAKE WAKE WAIT Normal audio streaming mode both nRF24Z1 units are on MCU wakes up periodically from its internal watchdog timer interrupt to poll the user interface for actions to be made If the Stop button is pressed the MCU powers down the system and sets powermode PMODE POWERDOWN Table 4 2 Combinations in User Interface Options 2 and 3 powermode wakeup Sleep mode PMODE POWERDOWN WAKE Z1 INT Faulty state as no interrupts should be sent from ATX nRF24Z1 to MCU ATX is wake on interrupt i e it will receive an interrupt to wake up not generate one PMODE POWERDOWN WAKE WAIT System 1s in sleep mode MCU polls buttons for wakeup command If ATX Play button is pressed try to wake up system If wakeup succeeds set powermode PMODE AWAKE PMODE AUTODOWN WAKE Z1 INT PMODE AUTODOWN WAKE WAIT The system went to automatic power down Check if ATX Play button is being pressed If it is try to establish a link and wake up system In the case of linkup success set powermode PMODE AWAKE PMODE AWAKE WAKE Z1 INT Faulty state as no i
31. No Yes Power down DAC x x Power down ARX Increase volume v DAC success y Power down ARX Y No Na Enable ATX auto power v down Y Power down ATX Pa Yes zu Sk Y Y A SCH Y Wake up ADC Power down ATX Yes rece P Power down ADC SS d y EA CM Y Wake up DAC Q St y Y PMODE POWERDOWN Decrease volume DAC success No Y Insert audio source on NG seguence eg LIS Y Lc N Yes E a N Wakeup ADO Lou Other button MCUprogram pressed Unmute ARX s N terminates j Y UM y Wake up DAC ec powermode Y Yes PMODE AWAKE No Insert audio source poweriniode control sequence y PMODE_AWAKE q 1 KA Y Enable ATX auto power Y down l gt Logicaldeboune 4 v 1 I C Figure 4 3 Flow chart of full user interface on ATX 4 5 2 Full UI on ARX User Interface Option 2 Very low power consumption in the ARX can be achieved if it 1s set to be wake on interrupt while in sleep mode The ATX is wake on timer That means that the ARX will only wake up when the user presses the Play button there There is no way to pass information from the Nordic Semiconductor ASA Vestre Rosten 81 N 7075 Tiller Norway Phone 47 72 898900 Fax 47 72 89 89 89 Revision 1 0 Page 21 of 59 Date January 2006 REFERENCE DESIGN nRF24Z1 Headphone Reference Design 1 nRF24Z1 HPR1 ATX to the ARX while in sleep mode Only RXPIN and RXMOD are sent Wakeup from automatic power down therefo
32. OLFSON WM8711L U301 IR302 10K IR301 10K Vestre Rosten 81 N 7075 Tiller Norway Page 49 of 59 i S lt o 82 S tinal 2E TEEN i ey d d Q S ty IK a x ae 8 KE END a ZS bf d E 9 4 e s 5 alL 2 el e ajojn jeja lt TIMA a 5 2 5 O S8 235 88 tf i d S mu O 8 5 O s 88 SEN t IL 4 a a Figure 5 8 ARX Board Audio Output DAC Phone 47 72898900 Fax 47 72 89 89 89 Date January 2006 REFERENCE DESIGN nRF24Z1 Headphone Reference Design 1 nRF24Z1 HPR1 BIM Battery Nordic Semiconductor ASA Revision 1 0 1 101 2 3 SW SPDT R101 0 ohm f U101 s IN OUT e Ci03 0 ohm Tonr R104 BYP 270K rem E Lem R103 Le amp apy 3 e tow LTI76IESS BYP 0 ohm 220K P501 1 2 B 4 5 6 E 8 9 1 Molex 54167 0208 Figure 5 10 ARX Board Daughterboard connector Vestre Rosten 81 N 7075 Tiller Norway Page 50 of 59 Phone 47 72 89 89 00 VDD_nRF VDD_A VDD_D nRF24Z1 supply ADC DAC analogue supply ADC DAC digital supply Fax 47 72 89 89 89 Date January 2006 REFERENCE DESIGN nRF24
33. REFERENCE DESIGN nRF24Z1 Headphone Reference nRD24 02 Design 1 nRF24ZI HPRI GENERAL DESCRIPTION The Nordic Semiconductor nRF24Z1 2 4GHz transceiver is the preferred device for use in wireless CD quality audio streaming products like headphones for Compact Disk MP3 and Mini Disk To show the feasibility of nRF24Z1 in such products a reference design system based on nRF24Z1 has been designed featuring the same functions as one may expect to find in a wireless portable headphone This document describes the nRF24Z1 Headphone Reference Design 1 nRF24Z1 HPR1 FEATURES e Audio transmitter ATX board with nRF24Z1 ADC MCU SMD antenna and 3 5mm jack female e Audio receiver ARX board with nRF24Z1 DAC SMD antenna and 3 5mm jack female Six pushbutton user interface on ATX and ARX boards ATX and ARX boards battery powered from two AAA cells CD quality audio performance 10 meters line of sight range Daughterboard featuring sockets for RS232 debugging in system programming of MCU and updating nRF24Z1 EEPROM e All boards are manufactured on a 1 6mm thick 2 layer FR4 substrate Nordic Semiconductor ASA Vestre Rosten 81 N 7075 Tiller Norway Phone 47 72898900 Fax 47 72 89 89 89 Revision 1 0 Page 1 of 59 Date January 2006 REFERENCE DESIGN nRF24Z1 Headphone Reference Design 1 nRF24Z1 HPR1 TABLE OF CONTENTS GENERAL DESCRIPTION E 1 FEATURES einan cas pan ao tekao meg eee eee 1 MEN uge E TE 4 GET EE 5 3
34. RS232 connectvor Axial Header 6 pin dual row Axial Header 10 pin dual row Axial Connector Molex 52435 3072 SMD Resistor 5 0603 Resistor 5 0603 Resistor 5 0603 Resistor 5 0603 Not fitted 0603 RS232 Transceiver Maxim MAX3218CAP SSOP20 Figure 6 2 Daughterboard BoM 6 3 Small PCB with the Molex 53916 0208 connector Schematic Figure 6 3 shows the circuit schematic for the small PCB with the Molex 53916 0208 connector P1 The Flat Flexible Cable is soldered to the P2 edge connector VDD_D P2 1 2 B ARX ATX board SS connection 7 VD BH i T a ily EE MOSI GE m Ge d np 2 4 Gees i e EE CSN S da FFC connection 5 1 MCU MOSI 6 16 ils MCU MISO zm TXD H 1 MCU RST S is RXD 19 10 20 A 1 RE Molex 53916 0208 22 23 S 25 26 LA 27 28 L 29 30 i Header 30 Figure 6 3 Small PCB with Molex 53916 0208 connector schematic Nordic Semiconductor ASA Vestre Rosten 81 N 7075 Tiller Norway Phone 47 72 898900 Fax 47 72 89 89 89 Revision 1 0 Page 55 of 59 Date January 2006 REFERENCE DESIGN nRF24Z1 Headphone Reference Design 1 nRF24Z1 HPR1 7 I 10 11 References Datasheet nRF24Z1 Preliminary Product Specification Rev 3 0 Nordic Semiconductor ASA Application Note nAN24 09 nRF24Z1 RF Layout
35. The simplified flowcharts in Figure 4 1 and Figure 4 2 below illustrate the way pairing and the user interface works in the Headphone Reference Design As can be seen from the figures pairing establishing a private address only takes place once after a battery power off on cycle That means that new audio connections can only be made between units that are recently reset User interface options 1 and 2 see Figure 4 1 behave very similarly in that the Play button must be pressed before the private address is established It also needs the Play button to be pressed in order to go back to audio streaming after the link is lost for a long time In option 1 only the ATX Play button will have the Play effect on the figure In option 2 only the ARX Play button will have the Play effect User interface option 3 see Figure 4 2 finds a private address immediately after both ARX and ATX are turned on It automatically resumes playing music if a lost link is found again Both ATX and ARX Play buttons have full effect in option 3 Nordic Semiconductor ASA Vestre Rosten 81 N 7075 Tiller Norway Phone 47 72898900 Fax 47 72 89 89 89 Revision 1 0 Page 14 of 59 Date January 2006 REFERENCE DESIGN nRF24Z1 Headphone Reference Design 1 nRF24Z1 HPR1 ATX ARX Insert Insert batteries batteries User ON User Play Se Establish User ON private address Receive new private address
36. There are three fundamental ways to design a user interface around the nRF24Z1 They differ in the sleep modes they use The three options are 1 Full user interface on ATX every UI function except power on at ARX 2 Full user interface on ARX every UI function except power on at ATX 3 Full user interface on both ARX and ATX The options will be explained in more detail in the following sections The three options are implemented in main optionl c main option2 c and main option3 c The Headphone Reference Design is set up with User Interface Option 3 The other modes can be tried out by changing main c and reprogramming the EEPROMs according to the description in the top of the main optionX c file Please also see section 4 8 for more information about reprogramming EEPROMs When you change the user interface option the project will have to be recompiled and the resulting main hex must be programmed into the ATX MCU by means of a STK500 or similar device for your chosen MCU 4 5 1 Full UI on ATX User Interface Option 1 With this option ATX is wake on interrupt while ARX is wake on timer This ensures very low power consumption in the ATX But the ATX will only wake up when the user presses the Play button on ATX There is thus no way to pass a command from ARX to ATX while the system is in sleep mode The ARX will occasionally try to establish a link This will succeed if the units are within range when the ATX is interrupted Wakeup from
37. Vestre Rosten 81 N 7075 Tiller Norway Phone 47 72898900 Fax 47 72 89 89 89 Revision 1 0 Page 30 of 59 Date January 2006 REFERENCE DESIGN nRF24Z1 Headphone Reference Design 1 nRF24Z1 HPR1 e void zl setflag char flag Write 0x01 to the nRF24Z transfer register at internal address flag This will initiate a transfer of certain registers from ATX to ARX e char zl haslink void Return 1 if the nRF24Z has found a link 0 if it has not To prevent false positives the function checks the internal LNKSTA register four times e char zl haslink wait void Check for a link repeatedly The function returns 1 when the link is found It returns 0 if no link is found after LINKFINDCOUNTER attempts each with a pause of LINKFINDPERIOD between them e void zl force relink void Re establish the nRF24Z 1 radio link For some register updates calling this function is the only way to synchronize contents from ATX to ARX e char zl mute arx char muting Change the ARX mute setting Calling the function with argument nut ing MUTEON will enable ARX muting silencing it Calling the function with argument muting MUTEOFF will disable ARX muting enable sound The function returns the value of a call to z1 1agready RXCSTATE performed before transferring new settings from ATX to ARX e void zl setprivateadr void Set a new private address by calling the internal random generator mcu randombyte for all the five address bytes This functi
38. Z1 Headphone Reference Design 1 nRF24Z1 HPR1 5 2 2 Layout plots Figure 5 11 shows the PCB layout and component placement for the ARX board EL I nRF2421 HPR1 ARX Co 0 CJ zon 24 75 Only battery holder B101 on bottom side 24 735 Bottom Layer seen from above Figure 5 11 ARX Board PCB layout Nordic Semiconductor ASA Vestre Rosten 81 N 7075 Tiller Norway Phone 47 72898900 Fax 47 72 89 89 89 Revision 1 0 Page 51 of 59 Date January 2006 REFERENCE DESIGN nRF24Z1 Headphone Reference Design 1 nRF24Z1 HPR1 5 2 3 Bill of Materials Designator Description Footprint Plastic battery holder Capacitor NPO 5 50V Capacitor NPO 5 50V Capacitor X7R 10 50V Capacitor NPO 5 50V Capacitor NPO 0 1 pF 50V Capacitor NPO 0 1 pF 50V Capacitor NPO 0 1 pF 50V Not fitted Capacitor X7R 1096 50V Capacitor X7R 10 50V Capacitor X7R 10 50V Capacitor NPO 0 1 pF 50V Capacitor X7R 1096 16V Capacitor X7R 1096 16V Capacitor X7R 1096 16V Capacitor X7R 1096 16V Capacitor X7R 1096 50V Capacitor Tantalum 2096 6V Capacitor Tantalum 20 6V ESR lt 3Q Capacitor Tantalum 20 20V Capacitor X7R 10 50V Capacitor Tantalum 20 6V ESR lt 3Q Capacitor X7R 10 16V Capacitor X7R
39. acitor NPO 596 50V Capacitor X7R 10 50V Capacitor NPO 596 50V Capacitor NPO 0 1 pF 50V Capacitor NPO 0 1 pF 50V Capacitor NPO 0 1 pF 50V Not fitted Capacitor X7R 1096 50V Capacitor X7R 10 50V Capacitor X7R 10 50V Capacitor NPO 0 1 pF 50V Capacitor X7R 10 50V Capacitor Tantalum 2096 6V Capacitor Tantalum 20 6V ESR lt 3Q Capacitor Tantalum 20 20V Capacitor X7R 10 50V Capacitor Tantalum 20 6V ESR lt 3Q Capacitor X7R 10 16V Capacitor X7R 10 16V Capacitor Tantalum 20 6V ESR lt 3Q Capacitor X7R 10 16V Capacitor X7R 10 16V Capacitor Tantalum 20 6V ESR lt 3Q Capacitor X7R 10 16V Capacitor X7R 10 16V Capacitor X7R 10 16V Capacitor NPO 5 50V Capacitor X7R 10 16V Capacitor NPO 5 50V Capacitor X7R 10 16V Capacitor X7R 10 16V Capacitor X7R 10 16V Capacitor X7R 10 16V Capacitor X7R 10 16V Capacitor X7R 10 16V Capacitor X7R 10 16V Capacitor X7R 10 16V Capacitor X7R 10 16V LED red Antenna Fractus FRO5 S1 N 0 102 Nordic Semiconductor ASA Vestre Rosten 81 N 7075 Tiller Norway Phone 47 72898900 Fax 47 72 89 89 89
40. board When the boards are powered up Battery ON OFF switch they broadcast on an initial address This address has to be chosen for your product or product family so that it will not have any unwanted compatibility with a competitor s product Once the ATX and ARX are both switched on and the user presses and holds the Play button the ATX will generate a random private address for the devices to use for the remaining time their battery power is Nordic Semiconductor ASA Vestre Rosten 81 N 7075 Tiller Norway Phone 47 72 898900 Fax 47 72 89 89 89 Revision 1 0 Page 12 of 59 Date January 2006 REFERENCE DESIGN nRF24Z1 Headphone Reference Design 1 nRF24Z1 HPR1 switched on This means that at Battery power ON any ATX may pair with any ARX within a product family A product family is made up of ATX and ARX devices that all share a common initial broadcast address DAC chip buttons definition and power saving scheme After one set of ATX and ARX has paired on a private address other devices in the same area may be paired too If you end up pairing with an unwanted device simply switch off on both ARX and ATX to try again If you want to create a new paired set within a product family simply switch off on the two devices you want to pair up All Headphone Reference Design ATX units are produced equally So are also all ARX units Please see section 4 2 for flowcharts that illustrate the way pairing and the user interface works in the
41. d or held the DAC is instructed to increase the audio volume Phone 47 72 89 8900 Fax 47 72 89 89 89 Date January 2006 Nordic Semiconductor ASA Revision 1 0 Vestre Rosten 81 N 7075 Tiller Norway Page 16 of 59 REFERENCE DESIGN nRF24Z1 Headphone Reference Design 1 nRF24Z1 HPR1 e Volume down when pressed or held the DAC is instructed to decrease audio volume e Stop brings the system into sleep mode e Play when the system is in sleep mode Play must be held for some time to wake the system up When the system is in audio streaming mode Play may be used as a play pause enter type button e Skip forwards may instruct audio source to go to next song e Skip backwards may instruct audio source to go to previous song All of this functionality is defined in software and may be redesigned for your product As is evident the majority of the common control buttons are not supported on the ATX and ARX PCBs Also the Headphone Reference Design has not been specified to pass commands onto an audio source For this the number of different audio sources is too large However the MCU source code detects and decodes all 12 common audio buttons and 3 more auxiliary buttons and lets you insert audio source control sequences for the buttons you choose to include in your design The power management source code also features comments stating where audio source commands should be inserted Up to 15 buttons may easily be accommodated o
42. down ATX down control sequence Y Y CH CO uw o Y Kl Logical debouse amp Nordic Semiconductor ASA Revision 1 0 O Figure 4 4 Flow chart of full user interface on ARX Vestre Rosten 81 N 7075 Tiller Norway Page 22 of 59 Phone 47 72 89 89 00 Fax 47 72 89 89 89 Date January 2006 REFERENCE DESIGN nRF24Z1 Headphone Reference Design 1 nRF24Z1 HPR1 4 5 3 Full UI on ARX and ATX User Interface Option 3 A full user interface on both ARX and ATX can be achieved at the cost of increased power consumption in sleep mode In order to pass information like power on commands both ways between ARX and ATX both have to be wake on timer while in sleep mode The timer parameters are set so that one unit typically the ARX is looking for a link for a very short time and then sleeps for a somewhat longer time before looking for a link again The other unit typically the ATX is slower and looks for a link for more than the duration of an awake asleep period of the faster unit The sleep period of the slow unit will therefore become rather long A trade off exists between the power consumption while in sleep mode and the time the user has to press and hold the Play button for music to appear In the Headphone Reference Design both ARX and ATX use a 1096 on time while in sleep mode The user then has to hold the Play button for more than two seconds However a benefit of both units bein
43. duction This document describes the nRF24ZI HPR reference design made by Nordic Semiconductor to show the feasibility of the nRF24Z1 in wireless headphone applications Nordic Semiconductor provides the following for the reference design This document Schematics in PDF and Altium Designer Protel 2004 format PCB layout in Gerber and Altium Designer Protel 2004 format Bill Of Material in PDF format Microcontroller source code in C and as HEX file zlconfig PC program Hardware o Reference design audio transmitter ATX board Reference design audio receiver ARX board A Daughterboard used for in system programming and debugging Flat Flexible Cable FFC with connector Nordic EEPROM programmer USB dongle USB cable OO oO 0 The first six items are available free of charge from Nordic Semiconductor s web page http www nordicsemi no The design files and the hardware are intended as an aid to customers wanting to use the nRF24Z1 in their own products The published design files have been made so that only small alternations like form factor and placement of user interface buttons are required to convert them into production ready files Nordic Semiconductor ASA Vestre Rosten 81 N 7075 Tiller Norway Phone 47 72 898900 Fax 47 72 89 89 89 Revision 1 0 Page 4 of 59 Date January 2006 REFERENCE DESIGN nRF24Z1 Headphone Reference Design 1 nRF24Z1 HPR1 2 Requirements In order to make full use of the Headphone Refe
44. en designing with the Nordic nRF devices the method to use is to initially base the matching towards the antenna on the standard 50 ohm matching network as given in the nRF device Product Specification The antenna impedance is measured with the antenna placed in the real application and with the application operating in its natural environments If the measured antenna impedance deviates significantly from 50 ohm extra matching components must be added in between our standard 50 ohm matching network and the antenna input to make the antenna look like a 50 ohm load In most situations you will be able to match towards any antenna impedance by adding a PI network that is shunt C or L series C or L shunt C or L in between our standard 50 ohm matching network and the antenna input Vector network analyzers are widely used for antenna impedance and VSWR Voltage Standing Wave Ratio measurements When measuring antenna impedance the antenna must be placed in the real application and the application must be operating in its natural environments e g hand held close to the ear etc After establishing the impedance value the graphical aid method of Smith chart is an effective way of designing the added impedance matching network For the Headphone Reference Design ATX and ARX boards a 1 5pF shunt capacitor to ground C12 in the RF Core schematics see Figure 5 1 and Figure 5 7 was needed for optimal impedance matching towards the Fractus ante
45. ep mode The ARX will listen occasionally using its initial address from EEPROM Once the user presses the Play button on ATX the system will relink on a private address and start playing music During consecutive sleeps the units will try to relink on the private address whenever Play is pressed on ATX Link tab in z1config e LNKETH 0x20 e LNKMOD 0x08 Mute when LNKERR gt LNKETH e NLCH 0x0F e ADDR use your preferred initial address This address must match that of function zl setinitialadr Interrupts tab in zlconfig e INTCF 0x02 Enable wakeup from power down interrupt Transmitter tab in z1config e I2SCNF_IN 0x80 Audio mode Master mode TXLAT 0x04 Nominal 20ms 48kHz TXWTI 0x01 TXLTI 0x31 TXSTI 0x0000 TXMOD 0xE2 RF DS TX pwr down 44 1 wake DD Receiver tab in zlconfig e RXSTA 0x40 Disable serial slave interface RXWTI 0x01 RXLTI 0x31 RXSTI 0x0030 RXWAKE 0x10 Wakeup on sleep timer I2SCNF_OUT 0x40 Mute sound RXMOD 0x20 RF DS 4 8 2 Full User Interface on ARX User Interface option 2 This setup puts the ARX in Wake on Interrupt sleep mode and the ATX in Wake on Timer sleep mode The ATX will listen occasionally using its initial address from EEPROM Once the user presses the Play button on ARX the system will relink on a private address and start playing music During consecutive sleeps the units will try to relink on the private address whenever Play is pressed on ARX Link tab in z1config e LNKETH 0x20
46. er for them to be paired again The reason is that a device that was once paired and then had its partner turned off will retain the private address it received and not go back to broadcasting on the initial address before it is switched off on This is because it is hard for it to know whether the partner was turned off or temporarily out of radio range It is possible to add a reset button to a nRF24Z1 device that will have the same effect as power cycling it This however has not been implemented on the Headphone Reference Design The Play and Stop buttons are inspired by those found on contemporary audio consumer electronics products There you typically see a CD player that powers down when the user presses Stop The CD player will power up and start playing again when the user presses Play In the Headphone Reference Design the Play button has to be pressed and held for some time for the play command to be recognized across an RF link that is in power save mode The In one of the three user interface options see section 4 5 the pairing will happen after Battery power ON in both ATX and ARX without the user having to press the Play button Nordic Semiconductor ASA Vestre Rosten 81 N 7075 Tiller Norway Phone 47 72898900 Fax 47 72 89 89 89 Revision 1 0 Page 13 of 59 Date January 2006 REFERENCE DESIGN nRF24Z1 Headphone Reference Design 1 nRF24Z1 HPR1 Headphone Reference Design does not have a control link to the audio source
47. erboard connector is probably not needed because assembly will use pre programmed MCU and EEPROM e The MCU functionality may be executed on the host MCU of the audio source e The contents of the configuration EEPROM may be offloaded to the MCU This is a matter of costs since the cost increase involved in a potential MCU upgrade might be higher than the cost of the EEPROM chip e The ADC is not needed if your source is digital e The 3 5mm female jack connector may be replaced by a direct connection to an analog audio source e Not all 6 user interface pushbuttons may be required in your finished product The ATX board circuit schematics PCB layout plots and Bill of Materials can be found in chapter 5 1 3 0 ARX board The ARX board consists of a nRF24Z1 transceiver a Fractus FROS S1 N 0 102 chip antenna a WM8711L DAC a configuration EEPROM a Daughterboard connector user interface pushbuttons user interface LED and two AAA batteries A 3 5mm female jack is used for connection to headphones or speakers In the ARX board cost and area reductions may include e The Daughterboard connector is probably not needed because the assembled EEPROM will be pre programmed Nordic Semiconductor ASA Vestre Rosten 81 N 7075 Tiller Norway Phone 47 72898900 Fax 47 72 89 89 89 Revision 1 0 Page 6 of 59 Date January 2006 REFERENCE DESIGN nRF24Z1 Headphone Reference Design 1 nRF24Z1 HPR1 e The 3 5mm female jack connector may be re
48. fine BTN AUX3 0500001111 AUX3 button Nordic Semiconductor ASA Vestre Rosten 81 N 7075 Tiller Norway Phone 47 7289 8900 Fax 47 72 89 89 89 Revision 1 0 Page 29 of 59 Date January 2006 REFERENCE DESIGN nRF24Z1 Headphone Reference Design 1 nRF24Z1 HPR1 In order to simplify function calls and constants certain IO definitions have been made These are listed here define LINKFINDCOUNTER 32 Max link locate attempts define LINKFINDPERIOD 32 Pause ms between link attempts define MAXPOLLITER 100 Max poll cycles before timeout define POLLDURATION 4 Pause between flag polls in ms define FLAGREADY 0x00 Transfer register ready define ZITIMEOUT 0x02 Transfer register nRF24Z1 timeout define OKAY 0x00 Request went well define TIMEOUT OxFF Request timed out define LINKPRESENT 0x01 A link is present define MUTEON 0x00 Turn on nRF24Z1 ARX muting define MUTEOFF 0x01 Turn off nRF2421 ARX muting define PMODE AWAKE 0x00 Awake streaming audio define PMODE POWERDOWN 0x01 Sleep power down mode entered define PMODE AUTODOWN 0x02 ATX nRF2421 automatic power down define INT VOID 0x00 No interrupt define INT LBROKEN 0x40 Int if link is broken define INT LQUAL 0x20 Int if link quality if poor define INT RTRANS 0x10 Int if remote transfer done define INT RINPUT 0x08 Int if remote
49. fortunately this is often the situation in most practical designs Because of this great care has to be taken when placing the antenna in a headphone design to ensure that the direction of maximum radiation from both the ATX and ARX unit antennas is pointing towards each other in most user situations When using chip SMD antennas please follow the antenna manufacturers guidelines very closely as regards placement of the antenna in the application and possible additional matching circuitry Use the technical support services available from the antenna manufacturer Antenna Characteristics Antenna Characteristics Nemko Comlab Nemko Comlab 18 JAN 2006 14 32 18 JAN 2006 14 29 Ref no 57841 3 Ref no 57841 3 CF 2404 000 MHz CF 2404 000 MHz Horisontal Polarization A dB div Vertical Polarization 5 dB div Horisontal Polarization Vertical Polarization Ref Lev 3 1dBm Ref Lev 1 7dBm Figure 3 2 ATX board Antenna radiation patterns 3 6 Daughterboard The Daughterboard features sockets for RS232 debugging in system programming of MCU and updating nRF24Z1 EEPROM In order to perform in system programming and RS232 debugging the Daughterboard has to be plugged onto either the ARX or ATX board All dongles and programming cables should be present in the Daughterboard during debugging Nordic Semiconductor ASA Vestre Rosten 81 N 7075 Tiller Norway Phone 47 72 898900 Fax 47 72 89 89 89 Revision 1 0 Page 10 of 59 Date January 2
50. g wake on timer is that recovery from auto power down will be automatic and not require user intervention Nordic Semiconductor ASA Vestre Rosten 81 N 7075 Tiller Norway Phone 47 72 898900 Fax 47 72 89 89 89 Revision 1 0 Page 23 of 59 Date January 2006 REFERENCE DESIGN nRF24Z1 Headphone Reference Design 1 nRF24Z1 HPR1 f N p 7 MCU startup 3 ATX is wake on timer it goes to rin is wake on timer it ma Su E automatic power down after 500ms automatic power down after 520ms Y without link ATX has a very sluggish without link ARX has a very fast wake Power down ADC NG wake sleep pattern at NO sleep pattern A X vc ATX nRF24Z1 m VLA active interaction Y needed devices only have to be Wait for ATX interrupt o in range MCU timeout p 2 w 4 Link found A PMODE AUTODOWN BEEN Both units are within PMODE_POWERDOWN range ATX nRF24Z1 active be WAKE Z1 INT Lh a WAKE WAIT Automatic WAKE z4 INT power down
51. h and meu atmega48 88 0c sss 34 4 7 Setup of AVR Studio STK500 and WinAVR e eeeeeeeee reser eee ener t notant 36 4 8 Setup of EEPROM and z E TE 36 4 8 1 Full User Interface on ATX User Option 1 eee 37 4 8 2 Full User Interface on ARX User Interface option 21 37 4 8 3 Full User Interface on ATX and ARX User Interface Option 3 38 5 Reference design circuit schematics PCB layout plots and BOM 40 5 1 MR 40 5 1 1 Schematl s PER 40 5 1 2 AONE PU ss ninn rn naa RE E TRE 44 5 1 3 Bill ug EE 45 OOMEES qoo 48 Nordic Semiconductor ASA Vestre Rosten 81 N 7075 Tiller Norway Phone 47 72 898900 Fax 47 72 89 89 89 Revision 1 0 Page 2 of 59 Date January 2006 REFERENCE DESIGN nRF24Z1 Headphone Reference Design 1 nRF24Z1 HPR1 5 2 1 SS EE 48 5 2 2 Layout E 51 5 2 3 Eeer 52 G DSU SMS DO cR 54 6 1 Daughterboard herberg 54 62 Daughterboard Bill of Materials cis succscusheeccsveiiseiaveiienneainieatun eaten eatin 55 6 3 Small PCB with the Molex 53916 0208 connector Schematic sseesseesseseseseesseee 55 SE NEE 56 5 YOUP NOLES EE 58 Nordic Semiconductor ASA Vestre Rosten 81 N 7075 Tiller Norway Phone 47 72 898900 Fax 47 72 89 89 89 Revision 1 0 Page 3 of 59 Date January 2006 REFERENCE DESIGN nRF24Z1 Headphone Reference Design 1 nRF24Z1 HPR1 1 Intro
52. h file for use with other DACs that may have bass boost char dac sleep void Puts the DAC into power save mode Returns RXEXEC state char dac wake void Wakes the DAC from power save mode Returns RXEXEC state char dac singlewrite char adr char data This function is used by the other DAC functions to transmit control sequences It is also used by the interactive debugger to access individual DAC data The address and data formats are like those described for adc singlewrite Returns RXEXEC state Implementations in mcu h and mcu atmega48 88 c The Headphone Reference Design has been designed with a Atmel Atmega48 MCU The Atmega88 is identical except for having 8kB of FLASH instead of the Atmega48 s 4kB While the smaller one fits in a finished product a larger MCU is well suited for application development and debugging mcu h features different functions that require hardware dependant implementation in the MCU These functions are called by other functions in the program If you choose to implement your product with a different MCU you have to write your own mcu xxxx c file However there should be limited need to rewrite mcu h mcu atmega48 88 c features hardware dependant register accesses and compiler dependant 4 include statements The top of the file describes the project s use of MCU IO pins void mcu init void Sets up the MCU with the right power save options This function also configures the MCU IO pins used
53. he antenna characteristics there is a 3 3pF ATX NOTE F iot Fitted R3 5 is only needed if in circuit programming of EEPROM is needed D o z X H lt Nordic Semiconductor ASA Revision 1 0 VDD nRF Q z 2 To daughterboard dE To microcontroller Figure 5 1 ATX Board RF Core Vestre Rosten 81 N 7075 Tiller Norway Phone 47 72 89 89 00 Page 40 of 59 ch o ec sw 19X l lwen n ox L3 amp s zLJE z l SE osi N E ssa L t 2 GES Ca ES i S CS wow L e S them B ie FI 828 H eae La 29 3H oos sim ED ge Nwaldoaos Ges e NOV i ERE E u 4 E Fer Ba gs 222 FEB S a RER i BS e 22295222 EE In H U d at a Fax 47 72 89 89 89 Date January 2006 REFERENCE DESIGN nRF24Z1 Headphone Reference Design 1 nRF24Z1 HPR1 AUDIO JACK 3 5 4 J301 3 oe 1 C3ll 220pF 25 4 C313 20pF I C309 C308 C307 d C306 0 luF 10u 0 luF 0 luF AT s x dd d z l je ae LO 2 3 ae vi fe 1 e d o s OM NG Ba 8 d OF 2 a s Z o E z3 e 2B VDD A C
54. hone Reference Design 1 nRF24Z1 HPR1 4 Software system design 4 1 Look and Feel When you first power on the Headphone Reference Design you will experience it from an end user s point of view This section therefore explains what behavior to expect from the boards An audio source has to be plugged into the ATX board and headphones into the ARX board Both the ATX and ARX boards have six pushbuttons and one power ON OFF switch In an end application the power supply system would typically consist of a rechargeable battery and charging electronics But for simplicity the Headphone Reference Design ATX and ARX boards are made with two AAA batteries and a power ON OFF switch There are three different ways to implement a Soft Power ON button with the nRF24Z1 These options are 1 Soft Power ON at ATX only not on ARX 2 Soft Power ON at ARX only and 3 Soft Power ON at both ATX and ATX The third option consumes more battery power than the other options It is important that you choose the option which is most suitable for your design as much of the Headphone Reference Design depends on this choice Please see section 4 5 for more detailed information about the three options Table 4 1 shows the placement of the user interface buttons on the ATX and ARX boards Volume Play Next Up Soft Power ON Song Battery Volume Stop Previous ON OFF Down Soft Power OFF Song Table 4 1 Button placement on ARX and ATX
55. in its range Link tab in z1config e LNKETH 0x20 e LNKMOD 0x08 Mute when LNKERRLNKETH e NLCH 0x0F e ADDR use your preferred initial address This address must match that of function zl setinitialadr Interrupts tab in zlconfig e INTCF 0x02 Enable wakeup from power down interrupt Transmitter tab in zl config e I2SCNF_IN 0x80 Audio mode Master mode e TXLAT 0x04 Nominal 20ms 48kHz e TXWTI 0x0D e TXLTI 0x03 Nordic Semiconductor ASA Vestre Rosten 81 N 7075 Tiller Norway Phone 47 72898900 Fax 47 72 89 89 89 Revision 1 0 Page 38 of 59 Date January 2006 REFERENCE DESIGN nRF24Z1 Headphone Reference Design 1 nRF24Z1 HPR1 e TXSTI 0x0075 e TXMOD 0x82 RF DS 44 1 Receiver tab in zl config e RXSTA 0x40 Disable serial slave interface e RXWTI 0x01 e RXLTI 0x33 e RXSTI 0x0009 e RXWAKE 0x10 Wakeup on sleep timer e I2SCNF_OUT 0x40 Mute sound e RXMOD 0x20 RF DS Nordic Semiconductor ASA Vestre Rosten 81 N 7075 Tiller Norway Phone 4772898900 Fax 47 72 89 89 89 Revision 1 0 Page 39 of 59 Date January 2006 REFERENCE DESIGN nRF24Z1 Headphone Reference Design 1 nRF24Z1 HPR1 S Reference design circuit schematics PCB layout plots and BOM 5 1 ATX Board 5 1 1 Schematics Figure 5 1 to Figure 5 5 shows the ATX board schematics DG cia change in the matching network compared to what is given in the nRF24Z1 Product Specification C7 is changed from 1 5pF to Due to t
56. in the nRF24Z1 After waking from an interrupt the ATX will try to establish a radio link for TXWTI TXLTI 1 10ms If this fails the ATX will go back to sleep mode Similarly if a pin change is detected on the selected pin s the ARX will try to establish a radio link for RXWTI RXLTI 1 10ms If this fails the ARX will go back to sleep mode Nordic Semiconductor ASA Vestre Rosten 81 N 7075 Tiller Norway Phone 47 72898900 Fax 47 72 89 89 89 Revision 1 0 Page 18 of 59 Date January 2006 REFERENCE DESIGN nRF24Z1 Headphone Reference Design 1 nRF24Z1 HPR1 4 4 5 Wake on Timer An internal low power timer in the nRF24Z1 may be used to make it try to establish a radio link at regular intervals While trying to establish a link the SPI or 2 wire slave control interface is active During this time the MCU will be able to access nRF24Z registers The time spent trying to establish a radio link is TXWTI 10ms for the ATX and RXWTI 10ms for the ARX The time spent sleeping between such attempts is TXSTI 1 256 TXSTI 0 10ms in the ATX and RXSTI 1 256 RXSTL_0 10ms in the ARX The time spent trying to establish a radio link is connected to the number of channels used for linkup NLCH R TXWTI lt 0x02 should only be used with NLCH OxOF Wake on Timer may not be combined with Wake on Interrupt inside the same chip The sleep mode for the ATX is selected in TXMOD while the sleep mode for the ARX is selected
57. input changed define INT LERROR 0x04 Int if link error is high define INT WAKE 0x02 Int if wake from power down 4 6 2 Implementations in main c and included files This file is used as a place holder that includes a file according to the chosen user interface option see section 4 5 It also holds global variables Include either main _optionl c main option2 c ormain option3 c The flow charts in Figure 4 3 Figure 4 3 and Figure 4 3 respectively will make the code easier to understand 4 6 3 Implementations in z1slaveio hand zlslaveio c This is a nRF24Z1 API written by Nordic Semiconductor for use with the Headphone Reference Design It is important that you know these functions before changing the rest of the program char z1 singleread char adr Read and return an 8 bit value from nRF24Z internal register at address adr The function forwards the call to the 2 wire master interface of the MCU It may be rewritten for an MCU SPI call in another application than the Headphone Reference design void zl singlewrite char adr char data Write 8 bit value data into nRF24Z1 internal register at address adr Relationship to SPI and 2 wire is the same as forz1 singleread char zl flagready char flag Return OKAY if the nRF24Z1 transfer register at internal address flag is ready Or return TIMEOUT if the flag register was not ready in MAXPOLLITER polls each lasting POLLDURATION ms Nordic Semiconductor ASA
58. link if power down define LED AUTODOWN 0b1000000010000000 Blink if automatic power down fendif User interface buttons are located on both ATX and ARX The definitions below map out the physical encoding of ARX buttons through DI 0 3 pins and into the RXPIN register The same encoding is used by the MCU to describe the buttons pressed on its GPIO pins That way the same code is processing both ATX and ARX buttons In the Headphone Reference design all buttons are active high In your design tie unused ARX DI pins to ground by means of resistors Even though the Headphone Reference Design only uses six buttons the MCU source code is able to decode all the buttons listed here define BTN NOKEY 0500000000 No button pressed define BTN PLAY 0500000010 Play pause power on define BTN VOLUP 0500001000 Volume up button define BTN VOLDN 0500000100 Volume down button define BTN STOP 0500000001 Stop and turn power off define BTN SKIPF 0500000011 Skip forwards button define BTN SKIPB 0500000101 Skip backwards button define BTN SCANF 0500001110 Scan forwards button define BTN SCANB 0500000111 Scan backwards button define BTN BBOOST 0500001001 Bass boost button define BTN RECON 0000001010 Reconnect button define BTN POWER 0500001011 Power button define BTN MUTE 0500001100 Mute audio output define BTN AUX1 0500001101 AUX1 button define BTN AUX2 0000000110 AUX2 button de
59. lt parameters stored in the ATX and ARX EEPROMs If you make any alterations the two EEPROMs should be programmed equally The setup in zlconfig depends on which user interface and power save option you choose With all three options start zlconfig version 3 0 0 0 and choose Restore factory default values from the Tools menu Then follow the instructions of the subsections below It is important to note that the RXEXEC and Read Write Transmitter Receiver Link Config buttons in zlconfig should not be used with the Headphone Reference Design These buttons communicate with the nRF24Z1 SPI slave interface through the CPLD on the evaluation boards Such a CPLD is not required for audio purposes and thus not featured on the Headphone Reference Design For development purposes only use the Program Read Verify EEPROM buttons under the EEPROG tab in zlconfig These buttons communicate with the SPI EEPROM connected to the nRF24Z1 master SPI ports by means of series resistors The resistors are there to prevent shorting between the master SPI port of nRF24Z1 and that of the Nordic USB dongle Nordic Semiconductor ASA Vestre Rosten 81 N 7075 Tiller Norway Phone 47 72898900 Fax 47 72 89 89 89 Revision 1 0 Page 36 of 59 Date January 2006 REFERENCE DESIGN nRF24Z1 Headphone Reference Design 1 nRF24Z1 HPR1 4 8 1 Full User Interface on ATX User Option 1 This setup puts the ATX in Wake on Interrupt sleep mode and the ARX in Wake on Timer sle
60. minal with UART ifdef DEBUG If the debug system and define DEBUG2W Enable debug of 2 wire interface define DEBUGIF Enter interactive debug interface at bootup define DEBUGDAC Report RXEXEC status from DAC writes define Z1UI Either enable nRF24Z1 ATX r w in debug interface define ADCUI Or enable ADC write only in debug interface define DACUI Or enable DAC write only in debug interface endif Global project defines let you choose which parts of this program to compile into your MCU Reducing the feature set will reduce the memory requirement Different API functions may be selectively included in your program Please see explanation below define ZLINTERRUPT Enable interrupt from nRF24Z1 to MCU define Z1ALTERADDRESS Enable address changes The user interface man machine interface may be configured by means of several defines The most important choice is which option to include in main c define USELED Use LEDs ifdef USELED If LEDs are used define some particulars define LEDON 0x01 IO definition turn LED on define LEDOFF 0x00 IO definition turn LED off define LED INITIAL 0b1111111111111111 Initial blink sequence define LED FAILURE 0b0001000100010001 Blink if failure define LED AWAKE 0b1010000000000000 Blink if awake define LED POWERDOWN 0b1000000010000000 B
61. mm stereo Axial Connector Molex 54167 0208 SMD Resistor 1096 0603 Resistor 1 96 0603 Resistor 596 0603 Resistor 596 0603 Resistor 596 0603 Resistor 596 0603 Resistor 596 0603 Resistor 596 0603 Resistor 596 0603 Resistor 596 0603 Resistor 0603 Resistor 0603 Resistor 0603 Resistor 1 0603 Resistor 1 0603 Resistor 5 0603 Resistor 5 0603 Resistor 5 0603 Resistor 5 0603 Power supply on off switch Axial User interface push button ALPS SKQMBBE010 SMD User interface push button ALPS SKQMBBEO0IO SMD User interface push button ALPS SKQMBBE010 SMD U U ser interface push button ALPS SKOMBBEO010 SMD ser interface push button ALPS SKQMBBE010 SMD User interface push button ALPS SKQMBBEO0IO SMD nRF24Z1 2 4GHz Transceiver for Audio Streaming QFN36L 6x6 EEPROM Microchip 25AA640 I SN 64K 1 8V SPI Bus Serial EEPROM SO 8 Voltage Linear Technology LT1761ES5 BYP 100mA regulator Low Noise LDO SOT 23 DAC Wolfson Microelectronics WM8711LGEFL Internet Audio DAC with Integrated Headphone Amplifier QFN5x5 28 Crystal C 9pF Co lt 7pF ESR lt 1000 SMD Frequency tolerance temperature stabillity lt 30 ppm Table 5 2 ARX BoM Nordic Semiconductor ASA Vestre Rosten 81 N 7075 Tiller Norway Phone 47 72898900 Fax 47 72 89 89 89 Revision 1 0 Page 53 of 59 Date January 2006
62. n an ARX PCB even without a microcontroller on that side of the system Please see schematic ARX Board RF Core in Figure 5 7 for an illustration of how diodes encode six buttons onto four pins in the Headphone Reference Design The button to input pin connections match the definitions around line 64inhpref defines h If you choose to include fewer buttons than the Headphone Reference Design simply omit them from the schematics and comment out their function in the file included in main c Unused input pins on the nRF24Z1 ARX should be grounded through resistors 4 4 Sleep Modes The nRF24Z1 features powerful mechanisms for power control This section describes the available power modes and how they are selected for use in the Headphone Reference Design The ATX is put into sleep mode when the power down bit in TXMODJ 6 is set to 1 Likewise the ARX is put into sleep mode when the power down bit in RXMOD 7 is set to 1 Seen from the MCU or user no attempt will be done to re establish an audio link as long as TXMOD 6 and RXMOD 7 are set However the status of ARX user interface buttons will be forwarded to the ATX at whenever both are searching for a link at exactly the same time To exit sleep mode both TXMOD 6 and RXMOD 7 must be cleared This must be done at a point in time when the ATX nRF24Z 1 is awake and ready to receive commands from the MCU on its 2 wire or SPI slave interface To exit sleep mode it is sufficient to
63. n or design Nordic Semiconductor does not assume any liability arising out of the application or use of any product or circuits described herein LIFE SUPPORT APPLICATIONS These products are not designed for use in life support appliances devices or systems where malfunction of these products can reasonably be expected to result in personal injury Nordic Semiconductor ASA customers using or selling these products for use in such applications do so at their own risk and agree to fully indemnify Nordic Semiconductor ASA for any damages resulting from such improper use or sale Reference Design Revision 1 0 Date 2006 01 26 Reference Design order code nRD24 02 All rights reserved amp Reproduction in whole or in part is prohibited without the prior written permission of the copyright holder Nordic Semiconductor ASA Vestre Rosten 81 N 7075 Tiller Norway Phone 47 72898900 Fax 47 72 89 89 89 Revision 1 0 Page 57 of 59 Date January 2006 REFERENCE DESIGN nRF24Z1 Headphone Reference Design 1 nRF24Z1 HPR1 8 Your notes Nordic Semiconductor ASA Vestre Rosten 81 N 7075 Tiller Norway Phone 47 72 898900 Fax 47 72 89 89 89 Revision 1 0 Page 58 of 59 Date January 2006 REFERENCE DESIGN nRF24Z1 Headphone Reference Design 1 nRF24Z1 HPR1 Nordic Semiconductor ASA World Wide Distributors For Your nearest dealer please see http www nordicsemi no ORD SEMICONDUCTOR Main Office Vestre Rosten 81
64. nRF24Z1 should have its own power supply line from the supply source The ADC DAC CODEC should also have their own separate digital and analogue supply lines In some designs an LC filter serial inductor and shunt capacitor on the analogue supply line to the ADC DAC CODEC might also be required A power supply distribution strategy based on star routing from a linear voltage regulator and proper supply decoupling at the ADC DAC nRF24Z1 devices has been implemented on the ATX and ARX boards of the Headphone Reference Design Power supply distribution strategy supply decoupling PCB layout and other important design issues for the nRF24Z1 the Wolfson Microelectronics ADC WM8951L and DAC WMS8711L have been carried out as recommended in the datasheets and available application notes for each device e PCB layout and de coupling guidelines and Application example chapters in the nRF24Z1 Product Specification e Application note nAN24 09 nRF24Z1 RF layout and the belonging RF layout gerber files e Application notes from Wolfson microelectronics o WAN 0129 Decoupling and Layout Methodology for Wolfson DACs ADCs and CODECs o WAN 0144 Using Wolfson Audio DACs and CODECS with Noisy Supplies Good ground layout is just as important as the power supply distribution strategy to ensure the best possible performance both from the nRF24Z1 and the ADC DACs In the Headphone Reference Design ATX and ARX boards a PCB with two layers ha
65. ng if an seguence ee P Bu entire MCU safety wait L Ready to receive period elapsed In E EA Power down ADC 1 ad lt Link founa gt YY Y Yes Kom P powermode Set new private address No fa PMODE AUTODOWN ion on m v Y Y x 7 fax FAN Wait for linku 1 1 m e NL No y Yes Button pressed on t P di 2 NG ARK Consider ATX buttons lt lt Link found O Y insert audio source on Yes sequence Yes x v Consider ARX buttons He Consider ARX buttons Yes N User brings Ge x p Wake up ADC system out of NG Power on remote DAC sleep mode nio SEP Y Ke mode Play pressed m powermode sou VODE AWAKE No Stop pressed DAC success Y No 1 H Yes YY Cy Yes M Insert audio source off E Yes Volume up ur sequence Wake up ADC No pressed v Disable ATX auto power Wake up DAC down Yes Power down DAC M X Y Increase volume Y Alter TXMOD for power Na Power down ARX ui Y d Y Y XS Power down ATX Alter RXMOD to attempt piu e No powerup Volume down Yes Y Yes lt pressed gt Power down ADC Unmute ARX Wait for linkup y y Y Insert audio source on Eee vow sequence ves PMODE_POWERDOWN powermode S MODE AWAKE Decrease volume Link found gt Na Y Wake up ADC v Y CA e Se A No Wake up DAC pis Y P S 2 i y L Other button N f MCU program Power down ARX pressed BE C terminates P Y powermode Enable ATX auto power PMOBE_AWAKE down Yes y x Y Enable ATX auto power No Insert audio source Power
66. nna in the 2 4GHz band Figure 3 1 below shows the ATX board measured antenna impedance and VSWR with the board close to the body and handheld for operation of the user interface push buttons The measurements were made with C12 1 5pF and with the rest of the matching network disconnected by removing L3 Antenna impedance VSWR Figure 3 1 ATX board measured antenna impedance and VSWR with two element matching network Due to the antenna radiation characteristics and to ensure sufficient harmonic suppression a change has been made in the matching network compared to what is given in the nRF24Z1 Nordic Semiconductor ASA Vestre Rosten 81 N 7075 Tiller Norway Phone 47 72 898900 Fax 47 72 89 89 89 Revision 1 0 Page 9 of 59 Date January 2006 REFERENCE DESIGN nRF24Z1 Headphone Reference Design 1 nRF24Z1 HPR1 Product Specification In the Headphone Reference Design capacitor C7 is changed from 1 5pF to 3 3pF This increased value of C7 together with C12 0 8pF ensures good output power at the fundamental good harmonic suppression and at the same time good impedance matching towards the antenna Please see 3 and 4 and the RF Core schematics in Figure 5 and Figure 5 7 Figure 3 2 below shows the ATX board measured antenna radiation patterns with horizontal and vertical polarization From these plots we can see that the radiation patterns are far from omni directional and un
67. nterrupts should be sent from ATX nRF24Z1 to MCU Nordic Semiconductor ASA Revision 1 0 Vestre Rosten 81 N 7075 Tiller Norway Page 26 of 59 Phone 47 72 89 89 00 Fax 47 72 89 89 89 Date January 2006 REFERENCE DESIGN nRF24Z1 Headphone Reference Design 1 nRF24Z1 HPR1 PMODE AWAKE WAKE WAIT Normal audio streaming mode both nRF24Z1 units are on MCU wakes up periodically from its internal watchdog timer interrupt to poll the user interface for actions to be made If the Stop button is pressed the MCU powers down the system and sets powermode PMODE POWERDOWN But before reading the remote and local buttons the MCU checks whether or not the ATX nRF24Z1 went to automatic power down If that was detected the MCU sets powermode PMODE AUTODOWN Table 4 3 Combinations in User Interface Optionl Most of main c deals with the different sleep modes powermode is a local variable in main c wakeup is a global variable written in mcu wait ms and SIGNAL SIG INTERRUPTO in mcu atmega48 88 c 4 6 MCU Source Code This section will describe the main features of the MCU source code The MCU source code is best understood if you start reading in the following order before making any alterations or attempting to compile it 1 This document 2 hpret defines h 3 main c and the file included in it The MCU source code is written in a modular fashion Here is a brief description of what the different files do
68. ogram the EEPROM Download files zIconfig 3 0 O zip and nRF24Z1 firmware 2 O hex from Nordic Semiconductor s web page http www index cfm obj product amp act display amp pro 86 See section 4 8 Nordic Semiconductor ASA Vestre Rosten 81 N 7075 Tiller Norway Phone 47 72 898900 Fax 47 72 89 89 89 Revision 1 0 Page 5 of 59 Date January 2006 REFERENCE DESIGN nRF24Z1 Headphone Reference Design 1 nRF24Z1 HPR1 3 Hardware system design The Headphone Reference Design consists of three parts an audio transmitter AT X board an audio receiver ARX board and a Daughterboard used for in system programming and debugging The system is controlled by a microcontroller MCU located on the ATX board A user interface consisting of six pushbuttons and one LED is present on both ATX and ARX boards The design has been made in a way that allows easy modification of the user interface All boards are manufactured on a 1 6mm thick 2 layer FR4 substrate 3 1 ATX board The ATX board consists of a nRF24Z transceiver a Fractus FRO5 S1 N 0 102 chip antenna a Atmel Atmega48 MCU a Wolfson WM8951L ADC a configuration EEPROM a Daughterboard connector user interface pushbuttons user interface LED and two AAA batteries A 3 5mm female jack connects to an audio source e g CD or MP3 player These parts are all needed to implement the Headphone Reference Design but in a finished product several components may be omitted e The Daught
69. on does no preceding check of LNKCSTATE nor does it write 0x01 to LNKCSTATE to actually transfer the new address settings This must be done in the function calling it zl setprivateadr may be selectively compiled into your program For this it requires ZLALTERADDRESS to be defined e void zl setinitialadr void Reset the initial broadcast address stored in ARX and ATX EEPROM Remember to update both your EEPROM settings and the initial address hard coded into this function Like z1_setprivateadr this function does not access LNKCSTATE in any way It also requires ZLALTERADDRESS to be defined e void zl arxled char mode Turn the LED on the ARX on or off This function is not very generic It is used with an active high LED on ARX general purpose output pin DO 1 The mode argument has to be either LEDON or LEDOFF to turn the ARX led on or off The function performs zl flagready RXCSTATE before writing to the ATX and zl setflag RXCSTATE afterwards The function may be selectively compiled into your program by defining USELED e char zl rotate led void The global 16 bit variable 1edsequence is rotated left Le the MSB is moved to the LSB in one rotate The function returns LEDON if the MSB shifted around is 1 and LEDOFF if it is 0 The function may be selectively compiled into your program by defining USELED e char zl intstatus void If an interrupt occurred this function will report which one was detected The
70. placed by a direct connection to headphones e Not all 6 user interface pushbuttons may be required in your finished product The ARX board circuit schematics PCB layout plots and Bill of Materials can be found in chapter 5 2 3 3 Power supply and current consumption The power supplies of the Headphone Reference Design ATX and ARX boards consist of only two AAA batteries and linear regulators ON OFF switches have been added for hard power on off in addition to soft on off in the user interface A finished application may omit the detachable AAA batteries and ON OFF switch and rather use rechargeable batteries with only soft power on off The power on reset effect of the ON OFF switch may then be replaced by a reset or reconnect button The Daughterboard is powered from the ATX or ARX board when it is connected The USB dongle output buffers receive its power supply from the same supply as the Daughterboard Table 3 1 below shows current in mA consumed from the two AAA batteries of the complete ATX and ARX boards The linear regulators are operating on 2 7V For explanations of Options 1 2 and 3 please see section 4 5 Onalone Streaming audio User power down Auto power down Option ATX 1 5 mA 31 1 mA 1 1 mA 0 9 mA ARX 2 9mA 32 0 mA 1 0 mA 5 0 mA Option2 ATX 2 9mA 30 8 mA 2 1 mA 1 5 mA ARX 2 6mA 32 2mA 0 3 mA 4 7 mA Option3 ATX 43mA 30 5 mA 3 2mA 2 8 mA ARX 5 0mA 32 8 mA 2 6 mA 7 2 MA Table 3 1
71. re requires user interaction on the ARX A typical application example is a wireless headphone which is worn while the audio source player is not available to the user A remote control on the headphone is therefore desirable Ne E ra is wake on timer it NA MCU startup automatic power down after 1000ms ARX goes directly to wake on interrupt without link During this time MCU has RXMOD must be set at a later stage In order for it to be able to power up SE ABG an to ATX ind a Ze v a e s 2 Prepare ARX to power MP User must Ln press Play on Y Hole Wait for ATX interrupt o ATX nRF24Z1 exit loop Menen ATX nRF24Z1 PMODE_AUTODOWN Ss MEN OU NEN UN User presses Play on ARX wakes system PMODE POWERDOWN from auto sleep mode gt lt wakeup WAKE WAIT Automatic WAKE zu INT e power down SL op detected 29 WAKE WAH ATX is wake on timer Insert audio source off Fr um y K something is wro
72. rence Design in your product development a certain level of knowledge and supporting programs and boards are required These are listed briefly here Detailed setup information may be found in sections 4 7 and 4 8 Knowledge of MCU programming in C is needed to perform modifications and adoptions in the supplied source code The source code is tested with the MCU and user interface present on the reference design If your hardware platform differs significantly for this modification of the C code is required The ADC and DAC chips used on the boards are supplied by Wolfson Microelectronics Nordic Semiconductor is not responsible for supporting Wolfson products Please consult the data sheets on http www wolfsonmicro com products digital audio dacs WMS871 1 and http www wolfsonmicro com products digital_audio adcs WM8951 If you choose to use the same MCU family Atmel AVR you will need to install AVR Studio http www atmel com dyn products tools card asp tool 1d 2725 WinAVR http winavr sourceforge net and a terminal emulator for example Tera Term http www ayera com teraterm All these programs are free of charge You will also need a means to do in system programming of the MCU For the Atmel AVR family use a STK500 development kit http www atmel com dyn products tools card asp tool id 2735 with an atmega48V or atmega88V MCU See section 4 7 You will need a Nordic Semiconductor USB dongle to pr
73. rogram No UALS ARE S pressed e terminates j v MC Pd LC Power down ARX Wait for linkup y nd Y powermode Yes Enable ATX auto power PMODESAWAKE No Insert audio source down control sequence Y Link found v MC P Enable ATX auto power Power down ATX Sa uu down eo Y Y i le ES SCH II Logical deboune NM C Figure 4 5 Flow chart of full user interface on both ARX and ATX 4 5 4 Identifying Sleep Modes in MCU Source Code In User Interface modes 2 and 3 the ATX nRF24Z 1 is set up to use the Wake on Timer sleep mode Thus the MCU will receive an interrupt from the IRQ pin whenever the ATX nRF24ZI1 wakes from sleep and tries to establish a link An important thing to notice is that this will Nordic Semiconductor ASA Vestre Rosten 81 N 7075 Tiller Norway Phone 47 72 898900 Fax 47 72 89 89 89 Revision 1 0 Page 24 of 59 Date January 2006 REFERENCE DESIGN nRF24Z1 Headphone Reference Design 1 nRF24Z1 HPR1 happen both when the MCU actively put the ATX nRF24Z1 into Wake on Timer sleep mode and when the ATX nRF24Z entered automatic power down The MCU program is of course able to know which commands it sent the ATX nRF24Z1 and which mode the system is in If the MCU receives an interrupt while being in Audio Streaming mode the ATX nRF24Z 1 has gone into automatic power down This is only the case when the ATX nRF24Z1 goes to Wake on Timer when it automatically powers down When an automatic power down is detected the MCU
74. special places in your code the following code is useful ifdef DEBUG Only include if DEBUG is defined mcu putchar X Print a single identifying letter endif End of selective compile The functions are e void db singleread char adr Reads a single byte from nRF24Z internal address adr and presents it on the UART e void db singlewrite char adr char data Writes a single byte data to a specific internal address adr of nRF24Z1 ADC or DAC depending on the debug defines made in hpre defines h The status is reported on the UART i e void db putenter void Prints DOS compatible newline characters r n e void db puthex char c Prints the hex number c on the UART e void db hex void This function starts an interactive debugging session with your terminal emulator monitoring the UART It lets you read and write single bytes into ATX nRF24ZI internal registers Please see the source code for more information on interactive debugging This function will run if DEBUG and DEBUGIF are both defined e void db showadr void Prints the currently set 40 bit device address This function is useful when monitoring your pairing process Nordic Semiconductor ASA Vestre Rosten 81 N 7075 Tiller Norway Phone 47 72 898900 Fax 47 72 89 89 89 Revision 1 0 Page 32 of 59 Date January 2006 REFERENCE DESIGN nRF24Z1 Headphone Reference Design 1 nRF24Z1 HPR1 4 6 5 Implementations in adc h and
75. t This file is hardware independent e dac wm8711 c Hardware dependent implementations of the functions declared in dac h This file is written for the Wolfson WM8711 DAC It and not dac h must be ported if you choose to design with a different DAC e mcu h Declarations of functions that must be rewritten if a different MCU is used This file is hardware independent e mcu atmega48 88 c Implementation of hardware dependent MCU functions for the Atmel Atmega48 and Atmega88 ICs These ICs are identical except for the size of their flash memory Architecture dependent include lt gt statements are featured at the top of mcu atmega48 88 h This file must be ported if you choose to design with a different MCU e makefile Project wide makefile for compilation with AVRGCC You must rewrite this file if you want to use a different compiler or MCU family The processor type is defined in the beginning of makefile 4 6 1 Definitions in hpref defines h For MCU speed define one of the following define MCU 8000 Either 8MHz internal RC oscillator define MCU 3686 Or STK500 3 686MHz oscillator define MCU 1000 Or 8MHz RC osc divided by 8 default in atmega48 88 If you use a development board to develop your application and this board has differing logic levels etc from those of your finished product choose your compilation target here For the Headphone Reference Design the ATX and ARX boards have active high buttons and
76. t of automatic power down The sleep mode variable powermode can be either PMODE POWERDOWN PMODE AUTODOWN or PMODE AWAKE The wakeup source variable wakeup can be either WAKE Z1 INT or WAKE WAIT Table 4 2 below shows the different combinations as they are used in User Interface Options 2 and 3 Table 4 3 shows the meanings of the combinations in User Interface Option 1 powermode wakeup Sleep mode PMODE POWERDOWN WAKE Z1 INT Normal sleep mode ATX nRF24Z1 is waking up the MCU by means of an interrupt The MCU will then check if a power on command Play button is received from the user interface If such a command is received the MCU powers on itself the ADC the ATX and the ARX before setting powermode PMODE AWAKE Nordic Semiconductor ASA Vestre Rosten 81 N 7075 Tiller Norway Phone 47 72898900 Fax 47 72 89 89 89 Revision 1 0 Page 25 of 59 Date January 2006 REFERENCE DESIGN nRF24Z1 Headphone Reference Design 1 nRF24Z1 HPR1 PMODE POWERDOWN WAKE WAIT System is asleep but no interrupt is received from ATX nRF24Z1 before the MCU safety period times out This is a faulty condition if ATX is Wake on Timer PMODE AUTODOWN WAKE Z1 INT PMODE AUTODOWN WAKE WAIT If the ATX is currently on i e trying to or succeeding in establishing a link check if a link is present If it is exit auto power down by powering up the ADC and setting powermode PMODE AWAKE P
77. treaming Mode the MCU in the Headphone Reference Design will use its own watchdog interrupt in order to keep track of time At regular intervals the MCU polls the user interface buttons on the ARX and ATX Depending on which button is pressed the MCU takes the appropriate action 4 4 6 Wakeup from Automatic Power Down Because automatic power down may put ATX and or ARX into either wake on interrupt or wake on timer different mechanisms are needed to bring the devices out of automatic power Nordic Semiconductor ASA Vestre Rosten 81 N 7075 Tiller Norway Phone 47 72 898900 Fax 47 72 89 89 89 Revision 1 0 Page 19 of 59 Date January 2006 REFERENCE DESIGN nRF24Z1 Headphone Reference Design 1 nRF24Z1 HPR1 down A device set to wake on interrupt has to be interrupted i e Play button pressed before it starts trying to re establish a link A device set to wake on timer will check for a link on a regular basis If both ARX and ATX are wake on timer and the sleep wake times are set correctly they will automatically wakeup from automatic power down Please note that the power down bits in RXMOD and TXMOD must both be cleared for the system to be able to wake up from automatic power down However as stated above if the user has chosen to power off the system the power down bits in RXMOD and TXMOD will be set and the units will not power on even if they are both searching for a link at the same time 4 5 User Interface Options
78. update TXMOD and RXMOD on the ATX side No transfer registers e g RXCSTATE have to be checked or set to exit sleep mode RXMOD is sent from ATX to ARX whenever both are on at the same time Nordic Semiconductor ASA Vestre Rosten 81 N 7075 Tiller Norway Phone 47 72898900 Fax 47 72 89 89 89 Revision 1 0 Page 17 of 59 Date January 2006 REFERENCE DESIGN nRF24Z1 Headphone Reference Design 1 nRF24Z1 HPR1 4 4 1 Automatic Power Down In addition to the user setting the power down bits in TXMOD and RXMOD the nRF24Z1 may automatically shut itself down when it looses its radio link for a certain time This feature is enabled in the ATX by writing a value 0x00 into TXWTI and in the ARX by writing a value Z 0x00 into RXWTI The power down bits in TXMOD and RXMOD will remain cleared while in automatic power down Therefore the ATX and ARX will be able to re establish a link any time they are within range and both searching for a link The reason for that the power down bits remain cleared is that they had to be cleared while streaming audio and when going to automatic power down access to the nRF24Z1 control slave interface is cut off The time that the devices will spend looking for a lost link before going to automatic power down is specified by TXWTI TXLTI 1 10ms in the ATX and RXWTI RXLTI 1 10ms in the ARX The devices will only go to automatic power down from audio streaming mode When automatic power down is enabled
79. upply R101 0 ohm R102 0 ohm Lone DZ i R103 T 10uF 0 ohm R105 220K Figure 5 4 ATX Board Power Supply VDD_D P501 Molex 54167 0208 Figure 5 5 ATX Board Daughterboard connector Nordic Semiconductor ASA Vestre Rosten 81 N 7075 Tiller Norway Phone 47 72898900 Revision 1 0 Page 43 of 59 VDD D ADC DAC digital supply Fax 47 72 89 89 89 Date January 2006 REFERENCE DESIGN nRF24Z1 Headphone Reference Design 1 nRF24Z1 HPR1 5 1 2 Layout plots Figure 5 6 shows the PCB layout and component placement for the ATX board a Il nRF 2421 HPRI d GEN Lj ca CI cs c3 E Ji de ti Me D SS En SR BBS E nmm frm SLI UL LU csi e qe FU uso 88 ai Suo P se Fd ki e L 4 wo an ni gg Ines N SU IC A E o DE R306 m R305 EJ 8 ss CT m EU 3401 3403 F bat d Pe eae UH LY L 402 505 ya Tl gsti Top Layer HO n P 28 7s gt v E Only battery holder B101 on bottom side Bottom Layer seen from above Figure 5 6 ATX Board PCB layout Vestre Rosten 81 N 7075 Tiller Norway Nordic Semiconductor ASA Page 44 of 59 Revision 1 0 Phone 47 72 89 89 00 Fax 47 72 89 89 89 Date January 2006 REFERENCE DESIGN nRF24Z1 Headphone Reference Design 1 nRF24Z1 HPR1 5 1 3 Bill of Materials Designator Description Footprint Plastic battery holder Capacitor NPO 596 50V Cap
80. ve been used All available areas on the top and bottom layers are flooded with ground plane The top layer ground plane areas are connected to the bottom layer ground plane areas through a large number of vias Please see the layout plots in chapter 5 1 2 and 5 2 2 and also the Headphone Reference Design gerber files 3 5 Antenna considerations The antenna used on the ATX and ARX boards is the Fractus FRO5 S1 N 0 102 chip SMD antenna http www fractus com img ds fr05 sl n 0 102 pdf The antenna has been placed onto the ATX and ARX boards according to the recommendations given in the Fractus antenna User Manual document UM FRO05 S1 N 0 102 and application note Wireless Headsets document AN FR05 S1 N 0 102 The Fractus User Manual and the application note are available on request from Fractus http www fractus com Environmental factors that affect the antenna impedance and radiation properties are parameters like shape of the PCB size of available ground plane proximity to housing housing material proximity to human body etc Changing one or more of these parameters in Nordic Semiconductor ASA Vestre Rosten 81 N 7075 Tiller Norway Phone 47 72 898900 Fax 47 72 89 89 89 Revision 1 0 Page 8 of 59 Date January 2006 REFERENCE DESIGN nRF24Z1 Headphone Reference Design 1 nRF24Z1 HPR1 an application will change the antenna impedance and hence demand for a new matching towards the antenna Wh
81. will power down the ADC but not the DAC because the control link is down It will also power down itself In User Interface Option 1 the ATX nRF24Z does not generate interrupts to the MCU when powering up But the interrupt pin ceases to be active when the ATX nRF24Z1 goes to automatic power down Hence this is detected by the MCU by polling the ATX nRF24ZI interrupt pin The opposite of entering automatic power down is coming out of automatic power down When this happens the MCU will have noticed that the system went to automatic power down at an earlier stage The interrupts that occur in User Interface Options 2 and 3 during wake on timer sleep mode will cease to occur The MCU will therefore have to rely on another wakeup source in addition to the external interrupt This additional wakeup source is its watchdog interrupt If in sleep mode and a certain wait period ends before the MCU receives the external interrupt the MCU checks if the nRF24Z1 system did just establish a link If this is the case the MCU will power up the ADC and itself In User Interface Option 1 the ATX is wake on interrupt An interrupt is sent from the MCU to the ATX nRF24Z1 when the MCU detects that the user is pressing the ATX Play button After receiving the interrupt the ATX nRF24Z 1 will try to establish a link for TXWTI TXLTI 1 10ms During this time the MCU will figure out if the ATX and ARX were able to establish a link If they did the system goes ou

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