Atmel AVR2080: REB231FE2
Contents
1. 5 i Transceiver AT86RF231 PBO SEL ISEL PB1 3 SPI On Board EEPROM CS The EEPROM data are written during board production testing A unique serial number the MAC address and calibration values are stored These can be used to optimize system performance Note Final products do not require this external ID EEPROM All data can be stored directly within the microcontroller s internal EEPROM Note 1 MAC addresses used for this package are Atmel property The use of these MAC addresses for development purposes is permitted Figure 3 3 shows a detailed description of the EEPROM data structure Atmel Atmel AVR2080 REB231FE2 Hardware User s Manual APPLICATION NOTE 6 8479B AVR 07 2012 Table 3 3 0x00 0x08 0x10 0x11 0x14 0x15 0x16 Ox17 0x18 0x20 Ox3E ID EEPROM mapping Name Type Description MAC address uint64 MAC address for the 802 15 4 node little endian byte order Serial number uint64 Board serial number little endian byte order Board family uint8 Internal board family identifier Revision _uint8 3 Board revision number Feature uint8 Board features coded into seven bits _ RA Reserved 6 Reserved 5 External LNA E External PA 3 Reserved 2 Diversity 1 Antenna 0 SMA connector Cal OSC 16MHz uint8 RF231 XTAL calibration value register XTAL TRIM Cal RC2. 8479B AVR 07 2012 Table of Contents 1 DisclaIMEN naa mana AGA LAAN 3 UN PU GA 3 3 Functional description ccc cccecceeeeeeeceeeeeeeeeeeeeaeeeaaeeaaeeaaeaaaasaaeeees 4 3 1 Interface connector 58 6 8 0 5 5 5 5 5 4 55 4 3 1 1 REB CBB Atmel ATxmega256A3 and Atmel STK501 Atmel ATxmega1281 configuration eire einen 5 3 1 2 Atmel ATmegab44 0 8 0 5 95 5 95535555550 09 5555555556 5 2 2 JIDIEEPISOM choses etas i D D cite cese Dabo ds 6 3 9 Supply current Sensiiig cotes retirer rhe NIAN eB 7 3 4 Radio transceiver reference clock ana nannnawwwaaanananannananaanaaannanasnananan ana 8 39 5 IRF SOCUOM ie NA NAL AA eiaei 9 4 PCB layout description sssssssssssssee Hee 10 44 PCB detail 1 balanced RF pin fan duta aaa 11 4 2 PCB detall 2 crystal routing scie eere oet APA 12 4 3 PCB analog GND toutilig irre ror BABALA pP ep ER IRE EUER ERR PURSE 12 44 PCB digital GND routing errem tnter h t Pe esera pne 13 AS PGB GND cf aranea E r aa 13 4 6 Ceramic antenna design and tuning es 13 5 Mechanical description 5 55554 4 5 888858
3. Medium access control MCU Microcontroller unit PA Power amplifier PCB Printed Circuit Board PDI Program debug interface PER Packet error rate R amp TTE Radio and Telecommunications Terminal Equipment Directive of the European Union REB Radio extender board RF Radio frequency RSSI Received signal strength indicator RX Receiver SPI Serial peripheral interface TX Transmitter XTAL Crystal Atmel Atmel AVR2080 REB231FE2 Hardware User s Manual APPLICATION NOTE 17 8479B AVR 07 2012 18 8479B AVR 07 2012 Atmel AVR2080 REB231FE2 Hardware User s Manual APPLICATION NOTE au 88 55 1 jo 2599 1 worsen Ibay aed an aa HAT og Setar 218 c3dieziepueixgoipey emt anga epped eui oi noon ON XexesamoN INDXdtoMALON Hue onowany TANAY ou pue do uo au ausa le P a sud song 534 45 Ec ds WIS 90 9 Anda anda auod PA Tas gan auod pa 7 lb
4. 90899 ana 6850 oN5a 0880 anga auod 0856 008 asn ayaw o mosa mosva lt 2 ji 6 a i 5 7 5 7 Appendix A A 1 Atmel 7 2 Assembly drawing Figure 7 2 Atmel REB231FE2 assembly drawing QN lt TO O OmO010 NG co KS R30 R6 C43 i GE f 888 7 1 J R g ATmega 644 TP4 eg ATmega 1281 40 Atmel Atmel AVR2080 REB231FE2 Hardware User s Manual APPLICATION NOTE 19 8479B AVR 07 2012 A 2 Bill of materials Table 7 1 Bill of materials Eger lamg lam Manuf Part Manufacturer Comment X2 X3 RF connector MS147 SMA CL358 150 5 06 Hirose MS147 1 X1 Pin header 2x20 90 JP 2x20 90 1007 121 40 CAB HEADER 20X2 degree Top Invers 1 U5 EEPROM MiniMap 8 2X3 AT25010B MAHL T Atmel AT25010B 1 U4 Logic gate MO 187 NV7WP32K8X Fairchild NC7WP32K8X 1 U3 802 15 4 2 4GHz MLF 32 AT86RF231 Atmel AT86RF231 radio transceiver 1 U6 Dual INV ULP SC 70 6 NC7WV04P6X Fairchild NC7WV04 1 U1 RFFE QFN24 SE2431L Skyworks SE2431L 9 R10 R11 R12 Resistor 0603H0 4 Generic 0Q R13 R14 R15 R16 R17 R18 1 R31 Resistor 0402 Generic 0Q 1 R8 Resistor 0402A Generic 4700 2 R7 R9 Resistor 0402A Generic 1MQ 1 R19 Resistor 0402A Generic 1 5kQ 1 R29 Re
5. The block diagram of the Atmel REB231FE2 radio extender board is shown in Figure 3 1 The power supply pins and all digital I Os of the radio transceiver are routed to the 2 x 20 pin expansion connector to interface to a power supply and a microcontroller The Atmel AT86RF231 antenna diversity AD feature supports the control of two antennas ANTO ANT1 A digital control pin DIG1 is used to control an external RF switch selecting one of the two antennas During the RX listening period the radio transceiver switches between the two antennas autonomously without the need for microcontroller interaction if the AD algorithm is enabled Once an IEEE 802 15 4 synchronization header is detected an antenna providing sufficient signal quality is selected to receive the remaining frame This ensures reliability and robustness especially in harsh environments with strong multipath fading effects Board specific information such as board identifier the node MAC address and production calibration values are stored in an ID EEPROM The SPI bus of the EEPROM is shared with the radio transceiver s interface Figure 3 1 REB231FE2 block diagram TP VDD ANT2 fl Protection AT86RF231 Mas 4 SPI ID EEPROM SE2431L EXPAND1 Interface connector specification The REB is equipped with a 2 x 20 pin 100mil expansion connector The pin assignment enables a direct interface to the REB CBB 2 Further t
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7. diagram SE2431L In transmit mode nominal antenna port transmit output power is 20dBm for Atmel AT86RF231 sub register setting TX PWR 0x0A at EVDD 3 0V nominal supply voltage Second and third harmonics levels are less than 42dBm MHz Transmit output power level is adjusted using the AT86RF231 TX output power controlled via register bits TX PWR The supply voltage can be increased to 3 6V to further increase transmit output power There is provision on the PCB for C L C low pass filtering at the antenna ports to reduce harmonic levels at these higher output powers In receive mode conducted sensitivity is better than 104dBm for 196 packet error rate The SE2431L has a typical receive noise figure of 2dB which includes all RF switch input losses Referring to the Atmel REB231FE2 schematic in Appendix A 1 the RF interface consists of two antenna ports By default two on board ceramic antennas are connected allowing radiated measurements Solder pads located along the tuning line allow for the optimization of antenna matching without the need for redesigning the PCB Detailed information about the antenna diversity feature is given in 1 and 3 Optionally two switched in line MS 147 RF connectors which disconnect the on board antennas allow conducted measurements The SE2431L antenna ports are controlled by AT86RF231 pin DIG1 connected to SE2431L pin ANT S
8. 012 3 4 The power supply pins of the radio transceiver and FEM are protected against overvoltage stress and reverse polarity at the EXPAND1 pins net CVTG net DGND using a Zener diode D1 and a thermal fuse F1 see Appendix A 1 This is required because the Atmel STK500 will provide 5V as default voltage and the board can also be mounted with reverse polarity Depending on the actual supply voltage the diode D1 can consume several milliamperes This has to be considered when the current consumption of the whole system is measured In such a case D1 should be removed from the board To achieve the best RF performance the analog EVDD AGND and digital DEVDD DGND supply are separated from each other by a CLC Pl element Digital and analog ground planes are connected together on the bottom layer underneath the radio transceiver IC Further details are described in Chapter 4 page 10 Note All components connected to nets DEVDD EVDD contribute to the total current consumption While in radio transceiver SLEEP state most of the supply current is drawn by the 1MQ pull up resistor R9 connected to the ID EEPROM and the EEPROM standby current Figure 3 4 Power supply routing F1 CVTG TT DEVDD EVDD MICROSMD035F DGND DGND DGND Radio transceiver reference clock The integrated radio transceiver is clocked by a 16MHz reference crystal The 2 4GHz modulated signal is derived from this clock Operating the node accor
9. 3 6V uint8 Atmel ATmega1281 internal RC oscillator calibration value 3 6V register OSCCAL Cal RC 2 0V uint8 Atmel ATmega1281 internal RC oscillator calibration value 2 0V register OSCCAL Antenna gain Int8 Antenna gain resolution 1 10dBi For example 15 will indicate a gain of 1 5dBi The values 00h and FFh are per definition invalid Zero or 0 1dBi has to be indicated as 01h or FEh Board name char 30 Textual board description CRC uint16 16 bit CRC checksum standard ITU T generator polynomial G16 x x 6 x tX 1 Figure 3 3 Example EEPROM dump CC EEPROM dump 0000 49 41 17 FF FF 25 04 00 D6 11 00 00 2A 00 00 00 Jp agad 0010 02 04 01 01 06 02 A8 A9 01 FF FF FF FF FF FF FF 0020 52 61 64 69 6F 45 78 74 65 6E 64 65 72 32 33 31 RadioExtender231 0030 46 45 32 00 00 00 00 00 00 00 00 00 00 00 8D 9B In 3 0040 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF 0050 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF 0060 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF 0070 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF 3 3 Supply current sensing A jumper JP1 is placed in the supply voltage trace to offer an easy way for current sensing of active components one the Atmel REB231FE2 see Figure 3 4 Atmel Atmel AVR2080 REB231FE2 Hardware User s Manual APPLICATION NOTE 7 8479B AVR 07 2
10. 4 Pin Function Pin Function 1 GND 2 GND 3 6 4 6 5 6 6 6 7 ne 8 9 6 10 6 11 6 12 6 13 6 14 6 165 me 16 n C 17 XT1 MCLK 18 n c 19 Vee 20 Vcc 21 GND 22 GND 23 PB7 SCLK 24 PB6 MISO Atmel AVR2080 REB231FE2 Hardware User s Manual APPLICATION NOTE 8479B AVR 07 2012 Pin Function Pin Function 25 PB5 MOSI 26 PB4 SEL 27 PB3 open 28 PB2 RSTN 29 PB1 MCLK 30 PBO open 31 PD7 SLPTR 32 PD6 DIG2 33 PDS TP2 34 PD4 open 35 03 TP3 86 PD2 IRQ 37 PD1 TP4 38 PDO open 39 GND 40 EE WP write protect EEPROM 3 2 ID EEPROM To identify the board type by software an optional identification ID EEPROM is populated Information about the board the node MAC address and production calibration values are stored here An Atmel AT25010B 8 with 128 x 8 bit organization and SPI bus is used because of its small package and low voltage low power operation The SPI bus is shared between the EEPROM and the transceiver The select signal for each SPI slave EEPROM radio transceiver is decoded with the reset line of the transceiver RSTN Therefore the EEPROM is addressed when the radio transceiver is held in reset RSTN 0 see Figure 3 2 Figure 3 2 EEPROM access decoding logic Atmel ATmega1281 configuration PB5 RSTN
11. 8559 14 6 Electrical characteristics 15 6 1 Absolute maximum ratings 5 5 55 55555 anan ener 15 6 2 Recommended operating range cemeterio ANAN 15 6 3 QuimentconsumplhlOn iies eiii ea AN GAAN HU pane bra Mie ee gna Foe a pra ce 15 6 4 Transmitter characteristics neeese iai a 16 6 5 Receiver characteristlos 16 7 Abbreviations ee 17 Appendix PCB design data 00 0 00 50 0050 000500050000000500059005 16 Aut SCNemalC AA P D NEED EDI 18 T 2 Assembly dEWIng tier rtt trt eo rhe 19 A2 Bilotimaterals heri Peer Raro De Ex EE CEP ERE anga Enc iS 20 Appendix B Radio 68 0 4555555555000909009 59555555505 21 B 1 United States FCC Rg 21 B2 EU OS D Ee 21 Appendix C 57 11 10 1116 MAN 23 Appendix D Revision history 5 55 eiie eaii a a Ea 24 Appendix 5 EVALUATION BOARD KIT IMPORTANT NOTICE 25 Atmel Atmel AVR2080 REB231FE2 Hardware User s Manual APPLICATION NOTE 2 8479B AVR 07 2012 1 Disclaimer Typical values contained in this application note are based on simulations and t
12. EL Atmel Atmel AVR2080 REB231FE2 Hardware User s Manual APPLICATION NOTE 9 8479B AVR 07 2012 The SE2431L operating mode is determined by control lines CTX CPS and CSD The default configuration connects CPS pin to EVDD via R31 This means that in receive mode the LNA will always be enabled for maximum sensitivity Enabling low power RX bypass mode requires removing R31 and R32 populated with OR resistor The PA is enabled when CTX is high and the LNA is enabled when CTX is low When CSD CTX and CPS pins are low the SE2431L goes into low current standby mode s1 A current consumption CSD is connected to the AT86RF231 analog LDO regulator output AVDD AVDD is 1 8V for all AT86RF231 states except P ON SLEEP RESET and TRX OFF To enable disable the SE2431L immediately and independently from individual radio transceiver states an additional GPIO control line from the microcontroller is required The SE2431L has two analog power supply pins VCC1 and VCC2 which power the internal analog circuitry This supply is connected to the REB231FE2 EVDD supply voltage The interface between the AT86RF231 and the Skyworks SE2431L is single ended 500 optimized for high performance and low cost applications The unused AT86RF231 RFN pin is terminated to ground with a 500 resistor and DC block Avoiding a balun helps minimizing the bill of materials cost In transmit mode the AT86RF231 transmit output power needs to be set higher compared to a diff
13. G K 1600 Technology Drive Unit 01 5 amp 16 19F Business Campus 16F Shin Osaki Kangyo Bldg San Jose CA 95110 BEA Tower Millennium City 5 Parkring 4 1 6 4 Osaki Shinagawa ku USA 418 Kwun Tong Road D 85748 Garching b Munich Tokyo 141 0032 Tel 1 408 441 0311 Kwun Tong Kowloon GERMANY JAPAN Fax 1 408 487 2600 HONG KONG Tel 49 89 31970 0 Tel 81 3 6417 0300 www atmel com Tel 852 2245 6100 Fax 49 89 3194621 Fax 81 3 6417 0370 Fax 852 2722 1369 2012 Atmel Corporation All rights reserved Rev 8479B AVR 07 2012 Atmel Atmel logo and combinations thereof AVR Enabling Unlimited Possibilities STK and others are registered trademarks or trademarks of Atmel Corporation or its subsidiaries Other terms and product names may be trademarks of others Disclaimer The information in this document is provided in connection with Atmel products No license express or implied by estoppel or otherwise to any intellectual property right is granted by this document or in connection with the sale of Atmel products EXCEPT AS SET FORTH IN THE ATMEL TERMS AND CONDITIONS OF SALES LOCATED ON THE ATMEL WEBSITE ATMEL ASSUMES NO LIABILITY WHATSOEVER AND DISCLAIMS ANY EXPRESS IMPLIED OR STATUTORY WARRANTY RELATING TO ITS PRODUCTS INCLUDING BUT NOT LIMITED TO THE IMPLIED WARRANTY OF MERCHANTABILITY FITNESS FOR A PARTICULAR PURPOSE OR NON INFRINGEMENT IN NO EVENT SHALL ATMEL BE LIABLE FOR ANY DIRECT INDIRECT CONSEQUE
14. I Atmel APPLICATION NOTE Atmel AVR2080 REB231FE2 Hardware User s Manual 8 bit Atmel AVR Microcontrollers Features e High performance 2 4GHz RF CMOS Atmel AT86RF231 radio transceiver targeted for IEEE 802 15 4 ZigBee and ISM applications 9 Industry leading 10408 link budget e Ultra low current consumption e Ultra low supply voltage 1 8V to 3 6V e High performance fully integrated 2 4GHz RF Front End Module SE2431L e Hardware supported antenna diversity e RF reference design and high performance evaluation platform e Interfaces to various Atmel microcontroller development platforms e Board information EEPROM e MAC address e Board identification features and serial number e Crystal calibration values Introduction This manual describes the Atmel REB231FE2 radio extender board supporting increased TX output power and RX sensitivity as well as antenna diversity The board is designed using the AT86RF231 radio transceiver in combination with the Skyworks SE2431L RF front end module FEM Detailed information is given in the individual sections about the board functionality the board interfaces and the board design The REB231FE2 connects directly to the REB controller base board REB CBB or can be used as an RF interface in combination with an Atmel microcontroller development platform The REB231FE2 together with a microcontroller forms a fully functional wireless node Figure 1 Top and bottom view of the REB231FE2
15. Ipp rx Pmin BUSY TX 5dBm 40 is 7 3 5 Supply current lIpp rx Paetauit BUSY TX 20dBm 116 7 3 6 Supply current Ipp rx Pmax BUSY TX 23dBm 205 8 F Note 1 Vpp 3 6V AT86RF231 sub register TX PWR 0x0 Atmel Atmel AVR2080 REB231FE2 Hardware User s Manual APPLICATION NOTE 15 8479B AVR 07 2012 6 4 Transmitter characteristics Test conditions unless otherwise stated Voo 3 0V fre 2 45GHZ Top 25 C TX_PWR 0xA X2 conducted Table 6 4 Transmitter characteristics i araneta co Maximum unit E 744 TX Output Power _Ch11 25 Ch26 1 4 420 235 dBm 7 4 2 Output Power Range 15 18 dB 7 4 8 Harmonics average worst case 4f0 50 44 dBm MHz 74 4 Spurious Emissions tbd dBm Notes 1 Ch26 requires TX 21040 power back off and duty cycle operation see Notes m details 2 Vpp 3 6V AT86RF231 sub register TX PWR 0x0 Notes 9 The Atmel REB231FE2 setup has been tested for compliance with FCC and ETSI see Appendix B To ensure compliance the following regional specific settings are to be ensured e FCC Operating the transmitter at channel 26 requires limitation of TX output power to max 13dBm and to ensure a duty cycle s2596 e FCC Operating the setup at maximum possible TX output power for all other channels requires either an adjustment of the lowpass filters C25 L3 C40 and C27 L2 C41 or alignment of the TX duty cycle e ET
16. NTIAL PUNITIVE SPECIAL OR INCIDENTAL DAMAGES INCLUDING WITHOUT LIMITATION DAMAGES FOR LOSS AND PROFITS BUSINESS INTERRUPTION OR LOSS OF INFORMATION ARISING OUT OF THE USE OR INABILITY TO USE THIS DOCUMENT EVEN IF ATMEL HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES Atmel makes no representations or warranties with respect to the accuracy or completeness of the contents of this document and reserves the right to make changes to specifications and products descriptions at any time without notice Atmel does not make any commitment to update the information contained herein Unless specifically provided otherwise Atmel products are not suitable for and shall not be used in automotive applications Atmel products are not intended authorized or warranted for use as components in applications intended to support or sustain life
17. SI Operating the setup in Europe requires setting the Atmel AT86RF231 register TX PWR to OxOE maximum for all channels This setting ensures compliance with ETSI EN 300 228 clause 4 3 2 2 Maximum Power Spectral Density refer to 6 6 5 Receiver characteristics Test conditions unless otherwise stated Vpp 3 0V fre 2 45GHz 3 Top 25 C X2 conducted Table 6 5 Receive characteristics No Parameter Condition Minimum Typical MENTA 7 5 1 Receiver Sensitivity PER lt 1 PSDU length 20 octets 104 7 5 2 Maximum RX input level C aa dBm 7 5 3 Spurious Emissions 70 7 54 RSSVED offset SE2431L LNA in high gain mode a Notes 1 Calculated based on AT86RF231 maximum RX input level SE2431L maximum RX gain 2 AT86RF231 RSSI value indicates RF input power PRF dBm RSSI BASE VAL 13 3x RSSI 1 see 1 in Chapter References 3 AT86RF231 ED value indicates RF input power PRF dBm 104 ED see 1 in Chapter References Atmel Atmel AVR2080 REB231FE2 Hardware User s Manual APPLICATION NOTE 16 8479B AVR 07 2012 7 Abbreviations AD Antenna diversity AES Advanced encryption standard BB Baseband REB CBB REB Controller base board ETSI European Telecommunications Standards Institute FCC Federal Communications Commission FEM Front end module ISM Industrial scientific and medical frequency band LDO Low dropout LNA Low noise amplifier MAC
18. ding to IEEE 802 15 4 4 the reference frequency must not exceed a deviation of 40ppm The absolute frequency is mainly determined by the external load capacitance of the crystal which depends on the crystal type and is given in its datasheet The radio transceiver reference crystal Q1 shall be isolated from fast switching digital signals and surrounded by a grounded guard trace to minimize disturbances of the oscillation Detailed layout considerations can be found in Section 4 2 The REB uses a Siward CX4025 crystal with load capacitors of 10pF and 12pF The imbalance between the load capacitors was chosen to be as close as possible to the desired resonance frequency with standard components To compensate for fabrication and environment variations the frequency can be further tuned using the radio transceiver register XOSC CTRL 0x12 refer to 1 The REB production test guarantees a tolerance of within 20ppm and 5ppm The correction value to be applied to TRX register XOSC CTRL 0x12 is stored in the onboard EEPROM see Section 3 2 The reference frequency is also available at pin CLKM of the radio transceiver and depending on the related register setting it is divided by an internal prescaler CLKM clock frequencies of 16MHz 8MHz 4MHz 2MHz 1MHz 250kHz or 62 5kHz are programmable refer to 1 The CLKM signal is filtered by a low pass filter to reduce harmonic emissions within the 2 4GHz ISM band The filter is designed to p
19. el transferred to the analog domain PCB GND plane Besides the function to provide supply ground to the individual parts the ground plane has to be considered as a counterpart for the antenna Such an antenna base plate is considered a continuous metal plane For that reason any unused surface should be filled with a copper plane and connected to the other ground side using sufficient through holes Larger copper areas should also be connected to the other side layer with a grid of vias This way for an external electromagnetic field the board will behave like a coherent piece of metal When a trace is cutting the plane on one side the design should contain vias along this trace to bridge the interrupted ground on the other side Place vias especially close to corners and necks to connect lose polygon ends Ceramic antenna design and tuning The antenna section follows an already existing similar implementation as described in Atmel AVR2043 REB231ED Radio Extender Board Hardware User Manual Rev 8345A AVR 05 11 Atmel Corporation 10 application note The application note provides detailed information about a design study design in and tuning Atmel Atmel AVR2080 REB231FE2 Hardware User s Manual APPLICATION NOTE 13 8479B AVR 07 2012 5 Mechanical description The Atmel REB231FE2 is manufactured using a low cost two layer printed circuit board All components and connectors are mounted on the top side of the board The for
20. erential TRX FEM interface using a balun In receive mode the effective gain ahead of the AT86RF231 is 3dB less than the specified SE2431L LNA gain 12 5dB The resulting loss in sensitivity is about 0 3 0 4dB Note The latest revision of SE2431L FEM 9 does not require resistor R30 connected to SE2431L pin 5 leave this pin unconnected as stated in the datasheet 4 PCB layout description This section describes critical layout details to be carefully considered during a PCB design The PCB design requires an optimal solution for the following topics e Create a solid ground plane for the antenna The PCB has to be considered as a part of the antenna it interacts with the radiated electromagnetic wave e Around the SE2431L front end module layout ensure good RF grounding good thermal conduction effective decoupling and correct microstrip impedances for RF tracks e Isolate digital noise from the antenna and the radio transceiver to achieve optimum range and RF performance e Isolate digital noise from the 16MHz reference crystal to achieve optimum transmitter and receiver performance e Reduce any kind of spurious emissions below the limits set by the individual regulatory organizations The Atmel REB231FE2 PCB design further demonstrates a low cost two layer PCB solution without the need of an inner ground plane The drawing in Figure 4 1 show critical sections using numbered captions Each caption number has its own subsection belo
21. ertification requirements an Original Equipment Manufacturer OEM must comply with the following regulations e The modular transmitter must be labeled with its own FCC ID number and if the FCC ID is not visible when the module is installed inside another device then the outside of the device into which the module is installed must also display a label referring to the enclosed module e This exterior label can use wording such as the following Any similar wording that expresses the same meaning may be used Contains FCC ID VNR E31F2 X5B 00 This device complies with Part 15 of the FCC Rules Operation is subject to the following two conditions 1 this device may not cause harmful interference and 2 this device must accept any interference received including interference that may cause undesired operation Use in portable exposure conditions FCC 2 1093 requires separate equipment authorization Modifications not expressly approved by this company could void the user s authority to operate this equipment FCC Section 15 21 Compliance Statement Part 15 105 b This equipment has been tested and found to comply with the limits for a Class B digital device pursuant to Part 15 of the FCC Rules These limits are designed to provide reasonable protection against harmful interference in a residential installation This equipment generates uses and can radiate radio frequency energy and if not installed and used in accordance with t
22. esting of individual examples Any information about third party materials or parts was included in this document for convenience The vendor may have changed the information that has been published Check the individual vendor information for the latest changes 2 Overview The radio extender board is assembled with an Atmel AT86RF231 radio transceiver 1 a Skyworks SE2431L FEM 9 and two ceramic antennas demonstrating an increased link budget together with hardware based antenna diversity improving radio link robustness in harsh environments significantly 3 The radio extender board was designed to interface to an Atmel microcontroller development platform The microcontroller board in combination with the REB provides an ideal way to e Evaluate the outstanding radio transceiver performance such as the excellent receiver sensitivity achieved at ultra low current consumption e Testthe radio transceiver s comprehensive hardware support of the IEEE 802 15 4 standard e Test the radio transceiver s enhanced feature set which includes antenna diversity AES high data rate modes and other functions The photograph in Figure 2 1 shows a development and evaluation setup using the REB CBB 2 in combination with the Atmel REB231FE2 radio extender board Figure 2 1 The REB231F2 connected to a REB CBB Atmel Atmel AVR2080 REB231FE2 Hardware User s Manual APPLICATION NOTE 3 8479B AVR 07 2012 3 1 Functional description
23. he ground connection in between the capacitors should be the crystal housing contact resulting in a compact robust and stable resonator The resonator block is enclosed within ground traces around it and a plane on the bottom side Do not connect the resonator directly to the plane beneath the block The only ground connection for the resonator block should be a trace in parallel with the two crystal lines that connects to TRX pin 27 or the paddle Based on recent experiments the bottom ground connection shall be routed directly to the paddle or pin 27 The loop is not required In addition the open space underneath the crystal can be filled with copper A small keep out trace next to the bottom ground connection can help to keep this connection separate and prevent the layout tool from flooding across this trace Figure 4 3 Board layout XTAL section When designing applications for very harsh environments for example where the radio transceiver is close to mains power lines and burst and surge requirements already dictate special provisions in the design the above reference crystal design might not work well In this case the reference crystal ground is to be directly connected to top and bottom layers PCB analog GND routing Analog ground pins 3 6 27 30 31 and 32 and pin 7 are to be routed to the paddle underneath the IC The trace width has to be similar to the pad width when connecting the pads and increase if po
24. he instructions may cause harmful interference to radio communications However there is no guarantee that interference will not occur in a particular installation If this equipment does cause harmful interference to radio or television reception which can be determined by turning the equipment off and on the user is encouraged to try to correct the interference by one or more of the following measures e Reorient or relocate the receiving antenna Increase the separation between the equipment and receiver e Connect the equipment into an outlet on a circuit different from that to which the receiver is connected e Consult the dealer or an experienced radio TV technician for help Warning Part 15 21 Changes or modifications not expressly approved by this company could void the user s authority to operate the equipment Europe If the device is incorporated into a product the manufacturer must ensure compliance of the final product to the European harmonized EMC and low voltage safety standards A Declaration of Conformity must be issued for each of these standards and kept on file as described in Annex Il of the R amp TTE Directive Atmel Atmel AVR2080 REB231FE2 Hardware User s Manual APPLICATION NOTE 21 8479B AVR 07 2012 The manufacturer must maintain a copy of the device documentation and ensure the final product does not exceed the specified power ratings and or installation requirements as specified in the user manual If any
25. he interface connects to the Atmel STK 500 501 microcontroller development platform to enable support for various Atmel 8 bit AVR microcontrollers The REB is preconfigured to interface to the REB CBB and STK501 with an Atmel ATmega1281 If an Atmel ATmega644 is used as the microcontroller the OQ resistors R10 through R18 must be removed and re installed on the board manually as resistors R20 through R28 see Appendix A 1 Other microcontroller development platforms need to be interfaced using dedicated adapter boards Atmel Atmel AVR2080 REB231FE2 Hardware User s Manual APPLICATION NOTE 4 8479B AVR 07 2012 3 1 1 REB CBB Atmel ATxmega256A3 and Atmel STK501 Atmel ATxmega1281 configuration Table 3 1 Default expansion connector mapping Pin Function Pin Function 1 GND 2 GND 3 n c 4 n c 5 n c 6 n c 7 6 6 6 9 6 10 6 11 nc 12 6 13 6 14 6 15 n c 16 n c 17 XT1 MCLK 18 n c 19 Vec 20 Vee 21 GND 22 GND 23 PB7 open 24 PB6 open 25 PB5 RSTN 26 PB4 SLPTR 27 PB3 MISO 28 PB2 MOSI 29 PB1 SCLK 30 PBO SEL 31 PD7 TP1 32 PD6 MCLK 33 PD5 TP2 34 PD4 DIG2 35 PD3 TP3 36 PD2 open 37 PD1 TP4 38 PDO IRQ 39 GND 40 EE WP write protect EEPROM 3 1 2 Atmel ATmega644 configuration Table 3 2 Expansion connector mapping when assembled for ATmega64
26. mat was defined to fit the EXPAND1 connector on the REB CBB and Atmel AVR STK500 STK501 microcontroller evaluation board The upright position is chosen for best antenna performance Figure 5 1 Mechanical outline E E o o ap Ce Ta y en m e g ATmega 644 af NG i i EE eg ATmega 1281 Cy KG x 40 ir 5 2 NI V I 4 iu Table 5 1 REB231FE2 mechanical dimensions Width x 57mm Height y 63mm Atmel Atmel AVR2080 REB231FE2 Hardware User s Manual APPLICATION NOTE 14 8479B AVR 07 2012 6 Electrical characteristics 6 1 Absolute maximum ratings Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the board This is a stress rating only and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of this manual are not implied Exposure to absolute maximum rating conditions for extended periods may affect device reliability For more details about these pa
27. nical or legal requirements that are applicable to finished products including without limitation directives regarding electromagnetic compatibility recycling WEEE FCC CE or UL except as may be otherwise noted on the board kit Atmel supplied this board kit AS IS without any warranties with all faults at the buyer s and further users sole risk The user assumes all responsibility and liability for proper and safe handling of the goods Further the user indemnifies Atmel from all claims arising from the handling or use of the goods Due to the open construction of the product it is the user s responsibility to take any and all appropriate precautions with regard to electrostatic discharge and any other technical or legal concerns EXCEPT TO THE EXTENT OF THE INDEMNITY SET FORTH ABOVE NEITHER USER NOR ATMEL SHALL BE LIABLE TO EACH OTHER FOR ANY INDIRECT SPECIAL INCIDENTAL OR CONSEQUENTIAL DAMAGES No license is granted under any patent right or other intellectual property right of Atmel covering or relating to any machine process or combination in which such Atmel products or services might be or are used Mailing Address Atmel Corporation 2325 Orchard Parkway San Jose CA 95131 Copyright 2012 Atmel Corporation Atmel Atmel AVR2080 REB231FE2 Hardware User s Manual APPLICATION NOTE 25 8479B AVR 07 2012 Atmel Enabling Unlimited Possibilities Atmel Corporation Atmel Asia Limited Atmel Munich GmbH Atmel Japan
28. of these specifications are exceeded in the final product a submission must be made to a notified body for compliance testing to all required standards The CE marking must be affixed to a visible location on the OEM product The CE mark shall consist of the initials CE taking the following form e Ifthe CE marking is reduced or enlarged the proportions given in the above graduated drawing must be respected e The CE marking must have a height of at least 5mm except where this is not possible on account of the nature of the apparatus e The CE marking must be affixed visibly legibly and indelibly More detailed information about CE marking requirements you can find at DIRECTIVE 1999 5 EC OF THE EUROPEAN PARLIAMENT AND OF THE COUNCIL on 9 March 1999 at Section 12 Atmel Atmel AVR2080 REB231FE2 Hardware User s Manual APPLICATION NOTE 22 8479B AVR 07 2012 Appendix C References 1 2 5 6 7 8 9 AT86RF231 Low Power 2 4GHz Transceiver for ZigBee IEEE 802 15 4 6LoWPAN RF4CE SP100 WirelessHART and ISM Applications Datasheet Rev 8111B MCU Wireless 02 09 Atmel Corporation Atmel AVR2042 REB Controller Base Board Hardware User Guide Application Note Rev 8334A AVR 05 11 Atmel Corporation AVR2021 AT86RF231 Antenna Diversity Application Note Rev 8158B AVR 07 08 Atmel Corporation IEEE Std 802 15 4 2006 Wireless Medium Access Control MAC and Physical Layer PHY Specifications f
29. or Low Rate Wireless Personal Area Networks LR WPANs FCC Code of Federal Register CFR Part 47 Section 15 35 Section 15 205 Section 15 209 Section 15 231 Section 15 247 and Section 15 249 United States ETSI EN 300 328 Electromagnetic Compatibility and Radio Spectrum Matters ERM Wideband Transmission Systems Data transmission equipment operating in the 2 4GHz ISM band and using spread spectrum modulation techniques Part 1 3 ARIB STD T66 Second Generation Low Power Data Communication System Wireless LAN System 2003 03 26 H11 12 14 Version 2 1 AT25010B SPI Serial EEPROM Datasheet Rev 8707C SEEPR 6 11 Atmel Corporation SE2431L 2 4GHz ZigBee 802 15 4 Front End Module SiGe Semiconductor Datasheet Rev 1 8 Aug 08 2010 Skyworks Solutions Inc 10 Atmel AVR2043 REB231ED Radio Extender Board Hardware User Manual Rev 8345A AVR 05 11 Atmel Atmel Corporation Atmel AVR2080 REB231FE2 Hardware User s Manual APPLICATION NOTE 23 8479B AVR 07 2012 Appendix D Revision history Version A08 1170 1 Description Initial release Atmel Atmel AVR2080 REB231FE2 Hardware User s Manual APPLICATION NOTE 24 8479B AVR 07 2012 Appendix E EVALUATION BOARD KIT IMPORTANT NOTICE This evaluation board kit is intended for use for FURTHER ENGINEERING DEVELOPMENT DEMONSTRATION OR EVALUATION PURPOSES ONLY It is not a finished product and may not yet comply with some or any tech
30. rameters refer to individual datasheets of the components used Table 6 1 Absolute maximum rating mie lg sl esum a 7 1 1 Storage temperature range 7 1 2 Humidity Non considerating 90 9o r H 7 1 3 Supply voltage 0 3 3 6 7 1 4 EXT I O pin voltage 0 3 Voc 0 3 a 7 1 5 Supply current from batteries Sum over all power pins 0 5 A 71 6 Battery charge current mA Note 1 Keep power switch off or remove battery from REB CBB when external power is supplied 62 Recommended operating range Table 6 2 Recommended operating range Minimum Typical uim wo E 2 1 Operating temperature range Note 7 22 Supply voltage Vcc REB231FE2 and REB CBB 0 2 3 0 3 6 V Note 1 Temperature range limited by crystal Q1 otherwise 40 85degC 6 3 Current consumption Test conditions unless otherwise stated Vpp 3 0V far 2 45GHz Top 25 C TX PWR 0XA X2 conducted Table 6 3 lists typical Atmel REB231FE2 current consumption values for different operating modes Current measurement is taken by replacing REB231FE2 jumper JP1 with an amperemeter for REB CBB figures refer to 2 Table 6 3 Current consumption of REB231FE2 JP1 Ce NC a Typical Maximum Unit 7 3 1 Supply current Ipp rRx orrF CLKM off 0 44 7 3 2 Supply current Ipp PLt_on SE2431L enabled RX mode 10 8 7616 Supply current Ipp Rx on SE2431L LNA high gain 17 6 7 3 4 Supply current
31. rovide a stable 1MHz clock signal with correct logic level to a microcontroller pin with sufficiently suppressed harmonics CLKM frequencies above 1MHz require a redesign of R8 and C36 In case of RC cut off frequency adjustments depending on the specific load and signal routing conditions one may observe performance degradation of channel 26 Note Channel 26 2480MHZz is affected by the following harmonics 155 x 16MHz or 310 x 8MHz Atmel Atmel AVR2080 REB231FE2 Hardware User s Manual APPLICATION NOTE 8 8479B AVR 07 2012 3 5 By default CLKM is routed to a microcontroller timer input check the individual configuration resistors in the schematic drawing To connect CLKM to the microcontroller main clock input assemble R3 with a 0Q resistor RF section The Atmel AT86RF231 radio transceiver incorporates all RF and BB critical components necessary to transmit and receive signals according to IEEE 802 15 4 or proprietary ISM data rates To further improve system TX output power and RX sensitivity a FEM is connected to the radio transceiver The Skyworks SE2431L FEM 9 is a high performance fully integrated module in a 3 x 4 x 0 9mm 24 pin QFN package It incorporates a transmit power amplifier PA with harmonic filtering a receive low noise amplifier LNA with optional bypass switch transmit receive TR switching and an antenna diversity switch A block diagram of the SE2431L is shown in Figure 3 5 Figure 3 5 SE2431L block
32. sistor 0402A Generic 1 2kQ 1 R30 Resistor 0402A Generic 113kQ 1 R6 Resistor 0201A Generic 49 90 1 Q1 Crystal 16MHz XTAL 4X2 5 XTL551150NLE Siward CX 4025 16MHz small 16MHz 9 0R 1 L1 SMT ferrite bead 0603H0 8 74279263 W rth 2200 9100MHz 2 L2 L3 Chip Inductor 0402 32306 L0075S80083LQG15 Murata 0 3nH HN 1 JP1 Jumper 2 pol JP 2x1 1001 121 002 CAB JP 2 1 F1 PTC fuse 1210 MICROSMD035F Tyco MICROSMD035F 1 D1 Z Diode DO 214AC BZG05C3V9 Vishay BZG05C3V9 1 C35 Capacitor 0402A Generic COG 12pF 5 3 C34 C38 C39 Capacitor 0402A Generic COG 10pF 5 4 C28 C29 C32 C33 Capacitor 0603H0 8 Generic X5R 1uF 4 C30 C31 C37 C42 Capacitor 0402A Generic X7R 100n 3 C11 C12 C43 Capacitor 0402A Generic COG 228 1 C36 Capacitor 0402A Generic COG 2 2pF 2 C1 C2 Capacitor 0402A Generic COG 3 3pF 2 C18 C26 Capacitor 0603A GRM1555C1H1RO Generic X5R 4 7uF CA01 4 C25 C27 C40 C41 Capacitor 0402A 2450AT45A100 Murata 1 0pF 0 25pF A1 A2 Ceramic antenna ANT AT45 45 Johanson 2 45GHz deg Atmel Atmel AVR2080 REB231FE2 Hardware User s Manual APPLICATION NOTE 20 8479B AVR 07 2012 Appendix B Radio certification B 1 B 2 The Atmel REB231FE2 mounted on a REB controller base board REB CBB has received regulatory approvals for modular devices in the United States and ensures compliance in European countries United States FCC Compliance Statement Part 15 19 The device complies with Part 15 of the FCC rules To fulfill FCC C
33. ssible some distance from the pad Atmel Atmel AVR2080 REB231FE2 Hardware User s Manual APPLICATION NOTE 12 8479B AVR 07 2012 Figure 4 4 Board layout transceiver GND 4 4 4 5 4 6 Each ground pin should be connected to the bottom plane with at least one via Move the vias as close to the IC as possible It is always desired to integrate the single pin ground connections into polygon structures after a short distance Top bottom and on multilayer boards the inner ground planes should be tied together with a grid of vias When ground loops are smaller than one tenth of the wavelength it is safe to consider this as a solid piece of metal The soldering technology used allows the placement of small vias 0 15mm drill within the ground paddle underneath the chip During reflow soldering the vias get filled with solder having a positive effect on the connection cross section The small drill size keeps solder losses within an acceptable limit During the soldering process vias should be open on the bottom side to allow enclosed air to expand PCB digital GND routing Digital ground pins 12 16 18 and 21 are not directly connected to the paddle Digital ground pins may carry digital noise from I O pad cells or other digital processing units within the chip In case of a direct paddle connection impedances of the paddle ground vias could cause a small voltage drop for this noise and may result in an increased noise lev
34. w with detailed information Atmel Atmel AVR2080 REB231FE2 Hardware User s Manual APPLICATION NOTE 10 8479B AVR 07 2012 Figure 4 1 Board layout RF section LIE SE SE aa M LIE NE SEE SEE LM ML M 4 1 PCB detail 1 balanced RF pin fan out Figure 4 2 Board layout SE2431L layout The SE2431L U1 and associated circuitry follow a standard Skyworks Solutions recommended layout to achieve specified RF performance The SE2431L requires a central PCB ground pad which is completely relieved of solder resist and has a grid of 15 ground vias 9 This is essential to achieve good RF performance and adequate thermal conduction especially in transmit mode The solder paste mask has limited coverage for assembly purposes The RF tracks to SE2431L TR ANT1 and ANT2 pins and tracking to the antennas are all 50O microstrip The 10pF decoupling capacitors C38 and C39 are placed close to the respective power supply pins Grounded pins on the SE2431L are routed directly to the central ground pad Atmel Atmel AVR2080 REB231FE2 Hardware User s Manual APPLICATION NOTE 11 8479B AVR 07 2012 4 2 4 3 PCB detail 2 crystal routing The reference crystal PCB area requires optimization to minimize external interference and to keep any radiation of 16MHz harmonics low The reference crystal and load capacitors C34 35 form the resonator circuit These capacitors are to be placed close to the crystal T
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