Atmel AVR2043: REB231ED - Hardware User manual 8
Contents
1. AMEL 2 8345A AVR 05 11 AIMEL Te A 3 Bill of materials Table 8 1 Bill of materials Designator Description Footprint Manuf Part Manufacturer Comment Phoenix 2 X2 X3 SMA Buchse SMA edge 1 5 142 0711 821 Johnson 522148603G 1 x1 EE cee re CAB HEADER 20X2 90 degree Top_Invers 1 U5 EEPROM MiniMap 8 2X3 een Atmel AT25010A 10YH 1 8 1 U4 Logic gate MO 187 NV7WP32K8X Fairchild NC7WP32K8X 1 U3 kr ee MLF 32 AT86RF231 Atmel AT86RF231 radio transceiver 2 U2 U6 Dual INV ULP SC 70 6 NC7WV04P6X Fairchild NC7WV04 U1 RF switch SC 70 6 AS222 92 SkyWorks AS222 92 R10 R11 R12 R13 9 R14 R15 R16 R17 Resistor 0603H0 4 Generic OO R18 R8 Resistor 0402A Generic 470Q R5 R6 Resistor 0402A Generic 2kQ R1 R2 R7 R9 Resistor 0402A Generic 1MQ XTAL 4X2 5 XTL551150NLE l 1 Q1 Crystal 16MHz small 16MHz 9 OR Siward CX 4025 16MHz 1 L1 SMT ferrite bead 0603H0 8 74279263 Wirth 2200 100MHz 1 JP1 Jumper 2 pol JP 2x1 1001 121 002 CAB JP 2 1 F1 PTC fuse 1812 miniSMDC020 Raychem miniSMDC020 1 D1 Z Diode DO 214AC BZG0O5C3V9 Vishay BZGO05C3V9 1 C35 Capacitor 0402A Generic COG 12pF 5 1 C34 Capacitor 0402A Generic COG 10pF 5 4 C28 C29 C32 C33 Capacitor 0603H0 8 Generic X5R 1uF 4 C25 C30 C31 C37 Capacitor 0402A Generic X7R 100n 2 C15 C22 Capacitor 0402A Generic COG 0 56pF C11 C12 C2. Figure 5 13 Final tuning 21 8345A AVR 05 1 1 AIMEL T Figure 5 13 page 21 and Figure 5 14 show the final result as a diagram and on the board 40 00 Se ates A JUL 10 00 10 00 SE AA A JUL 40 00 Pai 1 Start 2 3 GHz IERIW 70 kHz Stop 2 6 GHz EG In most cases it is beneficial to tune the antenna a little towards higher frequencies The reason is that environmental changes in most cases tune the antenna down to lower frequencies Such environmental changes can be any kind of object that is situated near the antenna such as a housing or table surface The tuning determined in this example is only valid for the antenna example board The REB231ED with its different ground plane design and many more differences may have other parts assembled 2 Atmel AVR2043 8345A AVR 05 1 1 Atmel AVR2043 6 Mechanical description The REB231ED 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 format was defined to fit the EXPAND1 connector on the Atmel AVR STK500 STK501 microcontroller evaluation board The upright position was chosen for best antenna performance Figure 6 1 Mechanical outline dimensions in mm Table 6 1 REB231ED mechanical dimensions with with y AIMEL 23 5 8345A AVR 05 11 ATMEL 7 Electrical ch
3. AMEL r Atmel AVR2043 REB231ED Hardware User manual 8 bit Atmel Features Microcontrollers e High performance 2 4GHz RF CMOS AT86RF231 radio transceiver targeted for IEEE 802 15 4 ZigBee and ISM applications Industry leading 104dB link budget Ultra low current consumption Hardware User Ultra low supply voltage 1 8V to 3 6V Man ual e Hardware supported antenna diversity e RF reference design and high performance evaluation platform e Interfaces to several of Atmel s microcontroller development platforms e Board information EEPROM MAC address Board identification features and serial number Crystal calibration values 1 Introduction This manual describes the REB231ED radio extender board supporting antenna diversity in combination with the Atmel AT86RF231 radio transceiver Detailed information is given in the individual sections about the board functionality the board interfaces and the board design The REB231ED connects directly to the REB controller base board REB CBB or can be used as an RF interface in combination with one of Atmel s microcontroller development platforms The REB231ED together with a microcontroller forms a fully functional wireless node Figure 1 1 Top and bottom views of the REB231ED 00 04 25 FF FF 1 IC GH CA AC RWZRZRZWZWZWZWZRW RW MZWWWZAM Eeeeeee e eeee ee eeee Rev 8345A AVR 05 11 2 Disclaimer 3 Overview 2 A
4. FAU s 1 I NOT Tu ropes isnot don E N EAEE EAEE E 1 ED ET EEE 2 NVE 2 4 Functional description axxaxxaxxnunnunnunnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnrnnrnnrnnnnnr 3 4 1 Interface Connector spechicaton ccc ececceeeeceeeeeeeeeeeeeeeeseeeeeeaeeeeesaeeeeesaeeeeeens 3 4 1 1 ATmega1281 configuration rronnrrnrnnrrrrnnnnenrnnnrrrrnnrerrnnererrnnrrnnnsnennnnsrennnnsrennnssennnnsee 4 4 1 2 ATmega644 configuration rrrrnnrrerrnnrrrrnnnrervnnnrerrnnrrnrnnrenrnnrrrnnnsnennnnsrennnnsennnnsennnnsee 4 A2 BE clos e EE 5 4 3 Supply current SENSING E 6 4 4 Radio transceiver reference cdock 7 e Ne EEE see eane deueuemnstecenaa 8 5 PCB Layout Description aa 9 5 1 PCB detail 1 balanced RF pin fan out 10 5 2 PCB detail 2 RF switch cc ccccccccccceeeceeeeeeceeeeeeeeeeeeeeeeeessseeeseeeeeeeeeeaeeeses 11 5 3 PCB detail 3 crystal routing n0nnnnnannenennnnnennnnennnnsnrnnenrnrsrnrennnrnrsrnrensnrrennnnn 11 54 PB fl MD 13 5 5 PCB digital GND routng 14 30 e E ER DING pirprssmauae E E EE EE E EEE 14 5 7 Ceramic antenna ccceecccccsecccceeeccceeeeccaueeeecsuuceeseuseeecseeesseaeeeessaeeeessagesessaass 14 5 7 1 Antenna design Study rrrnnnennnnorvnnnvnnnnennnnennnnsnnnnnennnsnvnnnennnnennnnennnnennnnnennnnennnnesnnn 14 5 7 2 Antenna design in beuegetreggeteueEAN Suerg egebetebeggefe de Se E Eege Neue EEN 17 SL AEE UN vasen 18 6 Mechanical description E 23 7 Electrical characteriStICS rr nrrnunnaunnn
5. 4 Functional description The block diagram of the REB231ED radio extender board is shown in Figure 4 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 4 1 REB231ED block diagram TP6 TP7 L O ANTO Me Protection RF Switch i AT86RF231 EEPROM IS IH EXPAND1 XTAL bonusen 4 1 Interface connector specification 8345A AVR 05 11 The REB is equipped with a 2 x 20 pin 100mil expansion connector The pin assignment enables a direct i
6. INHOOG 1409 SWENSSE D ex d o ES LE dl gjeos au ulun euusjuy 0 oe 6T d ou ir je dur Burun euusjuy F je u Burun euuazuy cad SS REEL Id 9 GU 8 16 602 BUS F 20 RE OG IG ELD ve CR w in 6 3 um ggg Ee A 0 SE ER ga e e a ON CH D D 00207 D D D D D 00207 OLAO p SLAJ on oN ad9s0 on oN a026 9N oN oN 34050 s Gr ae LN L 55 WNHOOS 1409 oweNnsselyZd ECH TCO L 079 Adel ch PL CL W i SSEJDIEN hm e z 1 K zitt old 69 80 19 LO 99 69 po 9 j S o P S H qog SCH I I T I Ker ot de T I I 9 s est zo WHO0S1d09 oss INHOOS 1409 SWENSSEIO 19 Sad e eS OIE PIOAE OF OA YIM sio sisal 9 qUEesse ANdA 7 aNod dog Jo sn yew o ZHOSH Z LX d017434 Ei Ss Re J N N bad mm LANVWdX3 LOSMLS Atmel AVR2043 26 8345A AVR 05 1 1 Atmel AVR2043 A 2 Assembly drawing Figure 8 1 REB231ED assembly drawing R11HR21
7. MCU 16MHz int RC 32MHz 2 Atmel AVR2043 8345A AVR 05 1 1 Atmel AVR2043 Supply current Supply current transceiver in state TRX ON transceiver in state BUSY TX 8 Abbreviations 8345A AVR 05 11 BB REB CBB NWA PDI REB RF SPI XOSC XTAL Baseband REB controller base board Network analyzer Program debug interface Radio extender board Radio frequency Serial peripheral interface Crystal oscillator Crystal AMEL 2 IMEL G Appendix A PCB design data A 1 Schematic 8 D 9 o r z OOGHIS VPA GaLETepuepgolpeydopseguefegs sbunes pue sjusWNs0q 9 Op GANDA Jee LC eege H 0107 08 4 21 POAMWZ 0801 4uly Z 0607 TaW LV ec Lg SSSEISPUET J YDENIGS IUSOX 00 00L 00 LL tt ez PAd ev SO ONOO lt uepsed 66010 LEZAH98 LY WS ONTON ae z TAWLY Pee Auen G3LEZJ9PUSIXJOPEN ani 920A AND ge S Hawg UEULSD TINLV GNDA cay pe ey on L961 WOLOSZLY u00 a 189 UND SNE O zl 3 31 Sy yjedusspun dM CN ONE EI EI 6 H 3 s pped au 0 Ape l be you pue do uo auejd CIOH OS aan zg ZA Ki o suid omg ONE aNov ONDYV GNDVINDV sud SSAC ANOYI SoN sig S ig aaaaa WOLOSZ LY 6186
8. can find at DIRECTIVE 1999 5 EC OF THE EUROPEAN PARLIAMENT AND OF THE COUNCIL on 9 March 1999 at section 12 1 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 2 AVR2042 REB Controller Base Board Hardware User Manual Application Note Rev 8334A AVR 08 10 Atmel Corporation 3 AVR2021 AT86RF231 Antenna Diversity Application Note Rev 8158B AVR 07 08 Atmel Corporation 4 IEEE Std 802 15 4 2006 Wireless Medium Access Control MAC and Physical Layer PHY Specifications for Low Rate Wireless Personal Area Networks LR WPANs 5 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 6 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 7 ARIB STD T66 Second Generation Low Power Data Communication System Wireless LAN System 1999 12 14 H11 12 14 Version 1 0 8 AT25010A SPI Serial EEPROM Datasheet Rev 3348J SEEPR 8 06 Atmel Corporation 8345A AVR 05 1 1 Atmel AVR2043 EVALUATION BOARD KIT IMPORTANT NOTICE 8345A AVR 05 1 1 This evaluation board kit is intended for use fo
9. 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 level transferred to the analog domain 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 EM 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 Part of the diversity board development was the evaluation of the antenna setup A dedicated board was designed to determine the key design parameters for a diversity antenna configuration Because the antenna has to operate in an environment different from that of the manufacturer s evaluation board the correct frequency tuning has to be verified The antenna dis
10. kHz Stop 2 6 GHz Hai CH Hald Stop ExtRef Ready Svc 2007 05 30 16 41 If practical situations are further analyzed see Figure 5 8 page 17 one can derive a practical antenna gain for the diversity setups To ensure robust and reliable communication a single antenna system has to consider at least a 30dB link margin as fade margin Considering the multipath setup used for the experiment a signal level of 70dBm is the worst case receiver signal strength when operating on antenna diversity A single antenna system could get into a spot where the receive power is as low as 85dBm It might be too optimistic in an indoor environment to take the 15dB and state that an antenna diversity system has four times the range compared to a non antenna diversity system But antenna diversity cuts deep fades and strongly increases the Stability of a radio link This is essential for radio nodes that get installed in a fixed position as with wall mounted equipment The location of deep fades can move over time due to small changes inside the room or building as there are doors windows furniture and people that may move 16 Atmel AVR2043 8345A AVR 05 1 1 Atmel AVR2043 Figure 5 8 Local fading effects in an indoor multipath environment AQ ee ooo a mn 45 receive signal strength dBm l EO i ERE EE EOE RENE
11. 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 5 3 page 11 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 Section References page 30 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 4 2 page 5 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 pro
12. or warranted for use as components in applications intended to support or sustain life 8345A AVR 05 11
13. 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 4 2 Figure 4 2 EEPROM access decoding logic ATmega1281 configuration PB5 RSTN RST Transceiver PBO SEL PB1 3 SPI On Board EEPROM CS The EEPROM data is 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 Final products do not require this external ID EEPROM All data can be stored directly within the microcontroller s internal EEPROM Table 4 3 shows a detailed description of the EEPROM data structure Table 4 3 ID EEPROM mapping Address name Type Description SS MAC address MAC address for the 802 15 4 node little endian byte order Board serial number little endian byte order Note MAC addresses used for this package are Atmel property The use of these MAC addresses for development purposes is permitted AMEL s AlmeL Addressiame Se Beer SSCS Board family Internal board family identifier uint8 3 Board revision number 0x14 Feature uint8 Board features coded into seven bits Reserved 6 Reseved ooo Antenna Oo SMA connector 0x15 Cal OSC uint8 RF231 XTAL calibration value register XTAL TRIM 16MHz 0x16 Cal RC 3 6V uint8 Atmel ATmega1281 internal RC oscillator calib
14. 1 DEI 9464 aNg aN9a sn 2A S 9dzL EE ny T l rn oC E n wei Ce of o at yeauepun Jefe i al at 8 wonoq uo auop 8q o Xu 135 a Z ANDY punog eNBbip Bojeue UONISUUO aa g 3 gg gr Fe a 570 0 L bei 0 S A EEE E LL TSN PS OO ZHIN9 SZOP XO ER SSAG 19261 u00 6A 090978 KO GAIA ei a SSAV aana er ZHINOOLOwuyooez p AGA zean agna dana aoaaa Fr SIND aaay TIEN Seng K 766 D 9 SSAV GE Kat Wlas un au ON gZ SSAV cold joy ES Dal L odd Dal L Zad ANDY SSAV Log 2700 7 ze 6 roid Y0 A1 ON 278 O So gt E E gt gt g 73S 0ad 73S vad LEZAHOBLV rem 0 en F P 7 F D e I Le op o ON 974 ISON C ER ISON C Gad TY66 D dl ANDY Y0 SLU ON SZA ov e fd ANDY OSIN ead OSIN 9ad 89264 89264 TY66 D dl sdzz 4dzz Y0 FLH ON FEH ear 470 979 L961 u00 FOAMCN BER L red YOS C 184 Be gr Si d cv66 0 ZMSau_ Y en X0 ELY ON ECH d en be N g 994 AND Beton 3da OW lad Se Sen TH66 0 0 0 S d e ma SA A sr 40 Eu ON SCH bd bd EGGG D 3 T ES cn 4 _ 1 a Big 2 Su Deg ved wlas Zad g bu amp 2766 0 9 o ap LIA ON Z Lem ei ANS unieg 5 a gt n jJ Le e Jo zold vad zold 9ad s TY66 D T aana X0 OL ON OZ Ee e anov 3 HESS NISH Gad VIS ER ek 2 Re EG adz R 669 Bco Byuoo Lo s L fou v Byuoo ppgebow LU ZE seen dl N TMS S tdl DEES Ge DE D I ryr y MA E A6 eal SSS ll gg ep dl D 0987 LZZS XUSOYd SSEIDJEN fi SSE DION DEOL ECS VUM E EE PE EX INHOOS 1409 SWENSSE D I r E
15. 26 C27 6 C38 C39 Capacitor 0402A Generic COG 22pF C3 C4 C5 C6 C7 C8 C9 C10 C13 C14 C16 C17 C18 0402A 28 C19 C20 C21 C23 Capacitor resistor 0603H0 4 Not assembled C24 R3 R20 R21 l R22 R23 R24 R25 R26 R27 R28 3 C1 C2 C36 Capacitor 0402A Generic COG 2 2pF B1 Balun 0805 6 748421245 W rth Balun SMD 2 A1 A2 Ceramic antenna o 2450AT45A100 Johanson 2 45GHz 23 Atmel AVR2043 8345A AVR 05 11 Atmel AVR2043 A 4 Radio certification The REB231ED mounted on a REB controller base board REB CBB has received regulatory approvals for modular devices in the United States and European countries A 4 1 United States FCC Compliance Statement Part 15 19 The device complies with Part 15 of the FCC rules To fulfill FCC Certification 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 E31ED 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 ca
16. Serr SEN E TE D EE G Single Antenna Dual Antenna hi Minimum worst case 1 ch d 85 i 1 CG y Diversity gain m a D 5 10 15 20 2 30 3 40 45 50 55 60 65 70 75 80 85 o 95 100 105 110 115 120 125 130 135 140 position cm 5 7 2 Antenna design in This section describes the antenna design in detail and the implementation of the antenna tuning structure An overview of the layout can be found in Figure 5 9 Figure 5 9 Antenna PCB environment and tuning structure AIMEL 17 E 8345A AVR 05 11 5 7 3 Antenna tuning 8 Atmel AVR2043 AIMEL a The antenna is available from two sources 1 Johanson 2450AT45A100 2 Wurth 7488910245 The antenna test board as specified by the manufacturers has a ground plane size of 20mm x 40mm an antenna placed in a 12mm x 20mm FR4 area and an FR4 substrate height of 0 8mm This is the expected environment where the antenna performance should be equivalent to the datasheet values On the REB231ED the environment differs considerably because the FR4 height is 1 5mm the antenna is placed in a triangular corner and the ground plane geometry is different too To compensate for the larger substrate height a 2mm not plated drill hole is placed underneath the antenna ceramic core see Figure 5 9 detail 1 The PCB ground is designed with a 45 degree angle along the red line Figure 5 9 detail 2 forming an optimum antenna ground reference The antenn
17. a local fading minimum Figure 5 8 page 17 shows the field strength plot for both antennas dependent on the board position For this test the antenna board was moved along a workbench using a stepper motor The transmitter was positioned several meters away on another workbench No direct line of sight connection is ensured using a large metal plate The graph shows receive signal strength variations caused by the interference of reflected waves reaching the receiver via different propagation paths AIMEL 15 E AIMEL T From Figure 5 8 page 17 one can conclude key parameters for such an indoor scenario 1 For one antenna multipath fades can exceed 30dB 2 For the 2 4GHz ISM band a local fading minimum is typically below 5cm 2in This number is expected considering the wavelength Conclusion an antenna diversity design should place antennas at a distance larger than that 3 For almost all positions only one antenna is in a deep fade The setup prepared for this test demonstrates the advantage of using antenna diversity Figure 5 7 Coupling between left and right antennas 1 Active ChiTrace 2 Response 3 Stimulus 4 Mkr Analysis 5 Instr State Trigger ER i i Hold Single 3 000 Hald All Channels 10 00 Continuous Disp Channels 12 00 Trigger SUG Internal 14 00 Trigger Ewent On Sweep Restart 16 00 Trigger 70 00 we H Start 2 3 GHz IERBIW 70
18. a tuning requires two more elements a series capacitor at the antenna feed point Figure 5 9 detail 3 and a capacitor that can be moved in position along the feed line Figure 5 9 detail 4 The series capacitor must be placed at the antenna feed point Under normal conditions only one capacitor is required within the detail 4 section of the PCB By choosing the correct footprint the capacitor can be moved along the line The impedance transformation across the transmission line depends on the distance between the antenna feed point and the capacitor in detail 4 resulting in the tuning effect The tuning procedure is explained in Section 5 7 3 The first step for the measurements is a board rework to access the RF line with a 500 coaxial cable In the case of the REB231ED the balun B1 was removed and a small rigid 50Q cable with an SMA connector was connected to the balun pin 1 pad The ground planes next to this feed point where used to create a solid ground connection for this cable This feed point will allow the measurement of both antennas because of the on board RF switch The RF switch was controlled by applying the correct voltage levels from a lab power supply 8345A AVR 05 1 1 8345A AVR 05 11 Atmel AVR2043 Figure 5 10 Antenna feed line short for extended length calibration The second step is to calibrate the network analyzer NWA to the 500 connector as usual After normal calibration the reference poi
19. aracteristics 7 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 parameters refer to individual datasheets of the components used Table 7 1 Absolute maximum ratings 74 3 supoywotage Lal me pr leie oa v rer 715 Supply current om bateries Sum over at powers J o Tas Baterycrarge curenn fo fm Note 1 Keep power switch off or remove battery from REB CBB when external power is supplied 7 2 Recommended operating range Table 7 2 Recommended operating range mo Parameter Eege minimum Typical Maximum Units 72 4 Operating enperatwerange mm mo fo 7 3 Current consumption Test conditions unless otherwise stated Vpo 3 0V Top 25 C Table 7 3 lists current consumption values for typical scenarios of a complete system composed of REB CBB and REB231 The Zener diode has been removed as described above Table 7 3 Current consumption of REB CBB populated with REB231 MCU power down Supply current transceiver in state SLEEP serial flash in Deep Sleep MCU 2MHz
20. ble can be fed through several ferrite beads The ferrite beads need to be placed close to the test board The initial measurement shows that the antenna is already working nicely in the desired frequency band The feed resistance is a bit low and the antenna has an inductive behavior AIMEL 19 E ATMEL ut lt gt 1 Start 2 3 GHz IFBWW 70 kHz Stop 2 6 GHz H The first tuning step will use the series capacitor to tune the band center down to a pure resistive behavior The band center is crossing the 30 degree 1 3 x Zo line Therefore the tuning capacitor can be determined by l C 27fXc with AC 500hm f 2 450GHz We get a capacitance of 3 89pF and can simply use a 3 9pF value The result of this tuning step can be seen in Figure 5 12 page 21 20 Atmel AVR2043 8345A AVR 05 11 Atmel AVR2043 Figure 5 12 Antenna tuning with series capacitor HUE 511 Smith Log Fhase Scale 1 0000 F2 Del Tr 511 Log Mag 10 00dB Ref 0 000dE Fe D t EO 00 sl 2 4 8 0689 dB 137712 gt 1 d 11 012 dE 151 28 f LI 40 Stop 2 6 GHz HAY 1 Start 2 3 GHz IFBW 70 kHz The final tuning step will use a shunt capacitor to correct the antenna load impedance A 0 5pF capacitor has been used to tune the antenna resonance frequency to the band center If the antenna resonance frequency is too low the capacitor needs to be moved towards the antenna and vice versa
21. cian 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 AMEL 2 8345A AVR 05 11 A 4 2 Europe ETSI References 30 Atmel AVR2043 AIMEL a 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 II of the R amp TTE Directive 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 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 If the 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
22. close to the crystal The ground connection in between the capacitors should be the crystal housing contact if available 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 12 Atmel AVR2043 8345A AVR 05 1 1 Atmel AVR2043 bottom ground connection can help to keep this connection separate and prevent the layout tool from flooding across this trace 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 5 4 PCB analog GND routing With the Atmel AT86RF231 consider pins 3 6 27 30 31 and 32 as analog ground pins Analog ground pins are to be routed to the paddle undernea
23. d can also be mounted with reverse polarity 6 Atmel AVR2043 8345A AVR 05 11 NOTE Atmel AVR2043 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 Section 5 page 9 A jumper JP1 is placed in the supply voltage trace to offer an easy way for current sensing to occur 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 4 4 Power supply routing F1 1 CVTG pa DEVDD EVDD 2200hm 100MHz 2229 miniSMDC020 C30 100n 19761 NT1 Net_Tie_2Net DGND AGND 4 4 Radio transceiver reference clock 8345A AVR 05 1 1 The integrated radio transceiver is clocked by a 16MHz reference crystal The 2 4GHz modulated signal is derived from this clock Operating the node according to IEEE 802 15 4 4 the reference frequency
24. ies inductance of 1nH to 2nH This is achieved with the connection fan out in between the IC pins and the DC blocking capacitors C26 and C27 The trace width is kept small at 0 2mm for a length of approximately 1 5mm The REB231ED is a two layer FR4 board with a thickness of 1 5mm Therefore the distributed capacitance between top and bottom is low and transmission lines are rather inductive 10 Atmel AVR2043 8345A AVR 05 1 1 Atmel AVR2043 5 2 PCB detail 2 RF switch Figure 5 3 Board layout RF switch The RF switch requires a solid grounding and RF filter capacitors for the control pins A parasitic inductance may reduce the RF isolation of the switch in the off state To achieve a hard low impedance ground connection a via is placed on each side of the ground pad Additionally the ground pad is connected to the top layer ground plane Blocking capacitors C38 and C39 are placed as close as possible to the RF switch to short any control line noise avoiding parasitic amplitude modulation of the RF signal 5 3 PCB detail 3 crystal routing The reference crystal PCB area requires optimization to minimize external interference and to keep any radiation of 16MHz harmonics low AIMEL 11 8345A AVR 05 11 AIMEL E Figure 5 4 Board layout XTAL section l femme mmm Guard GND The reference crystal and load capacitors C34 35 form the resonator circuit These capacitors are to be placed
25. nnectors can be assembled if conducted measurements are to be performed Refer to the schematic and populate coupling capacitors C11 C12 and C18 C19 accordingly 8345A AVR 05 1 1 Atmel AVR2043 5 PCB Layout Description 8345A AVR 05 11 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 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 REB231ED PCB design further demonstrates a low cost two layer PCB solution without the need of an inner ground plane The drawing in Figure 5 1 shows critical sections using numbered captions Each caption number has its own subsection below with detailed information Figure 5 1 Board layout RF section zem O o Po AIMEL 9 AIMEL a 5 1 PCB detail 1 balanced RF pin fan out Figure 5 2 Board layout RF pin fan out The Atmel AT86RF231 antenna port should be connected to a 1000 load with a small ser
26. nt for the NWA is at the cable SMA connection To determine the tuning elements the reference point has to be moved to the antenna feed point using the extended length parameter inside the NWA To determine this parameter a hard short is required at the antenna feed line end Remove the solder resist on the left and right sides of the feed line end and short the line end to ground with two solder bumps see Figure 5 10 page 19 Do not use any wires to create a ground connection The calibration procedure will only work when the short is exactly at the line end and has a minimum of parasitic inductance Now the NWA extended length parameter can be adjusted until the NWA s Smith chart displays a nice short for the desired frequency range In the third step the antenna behavior can be measured without any tuning elements To see the real antenna behavior the board must be placed in a position similar that of the final application If the final application has a housing installed then all these measurements must be done with the housing attached Any piece of metal or plastic can tune the antenna to a different frequency In the case of small boards with an edge length of less than 10cm the connected RF cable is often a source of measurement errors The outer conductor of the coaxial cable could interact with the field radiated by the antenna and therefore create an additional counterpart ground for the antenna To avoid this effect the coaxial ca
27. nterface to the REB CBB 2 Further the interface connects to the Atmel STK500 501 microcontroller development platform to enable support for various Atmel 8 bit AVR microcontrollers The REB is preconfigured to interface to an 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 Exhibit A 1 Other microcontroller development platforms need to be interfaced using a special adapter board AMEL s ATMEL 4 1 1 ATmega1281 configuration Table 4 1 Default expansion connector mapping eine configuration np Ponens len 25 posen T Paer 4 1 2 ATmega644 configuration Table 4 2 Expansion connector mapping when assembled for ATmega644 Par rene en ele fa lw 4 Atmel AVR2043 8345A AVR 05 11 4 2 ID EEPROM 8345A AVR 05 11 Atmel AVR2043 Pint Function em Function PBO pen P02 RO 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 AT25010A 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
28. r FURTHER ENGINEERING DEVELOPMENT DEMONSTRATION OR EVALUATION PURPOSES ONLY It is not a finished product and may not yet comply with some or any technical 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 users 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 2009 Atmel Corporation AMEL d 9 Table of contents 322 Atmel AVR2043
29. ration value 3 6V register OSCCAL 0x17 Cal RC 2 0V juint8 Atmel ATmega1281 internal RC oscillator calibration value 2 0V register OSCCAL 0x18 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 char 30 Textual board description Ox3E CRC uint16 16 bit CRC checksum standard ITU T generator polynomial G16 X x e x x 4 1 Figure 4 3 Example EEPROM dump HELE EEPROM dump 0000 49 41 17 FF Fr 25 04 00 D6 11 00 00 2A 00 00 00 EE ae ee add 0010 02 04 01 01 06 02 A8 A9 OL FF FF FF FF FF FF ERT g Ee 0020 52 61 64 69 6F 45 78 74 65 6E 64 65 72 32 33 31 RadioExtender231 0030 45 44 00 00 00 00 00 00 00 00 00 00 00 00 8D 9B EDs seces ereas uas AN EE EE ER EE EER EE ER EE EE EE ER EE CEECEE EER EE are a E E e a 0050 te EE FF EEFE FF EE EFE EE FE EE EE EF FE EE EE i ch Sa cS hc hc a 0060 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF Es aaa ete eer ete Beet es 0070 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF UT PE 4 3 Supply current sensing The power supply pins of the radio transceiver 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 Exhibit A 1 This is required because the Atmel STK500 will provide 5V as default voltage and the boar
30. rms 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 CONSEQUENTIAL 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 product 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
31. tance required for optimum diversity operation provides enough board space to use a low cost tuning method based on a transmission line and capacitors The actual tuning procedure is explained in Section 5 7 3 page 18 8345A AVR 05 1 1 Atmel AVR2043 Figure 5 6 Initial antenna tuning and test board 8 n Besides the antenna tuning the test board was used to measure the diversity effect and the coupling between the two antennas The better the two antennas are isolated from each other the higher is the diversity advantage for the receiver It has to be considered that the unused antenna is operating against an open line end because the RF switch U1 has high impedance in the off position A low coupling in between the antennas is therefore required Direct coupling measurement results between both antennas are shown in Figure 5 7 page 16 Over the operating frequency range the antenna separation is gt 15dB That is achieved mainly with the 45 degree installation The 90 degree turn between left and right antennas causes orthogonal radiation patterns and minimal coupling Because the polarization of a received wave is not deterministic in a multipath environment this setup is also capable of selecting the optimum polarization match for an incoming wave The other design aspect is the antenna distance The antenna distance has to be large enough to ensure only one of the two antennas is present in
32. th the IC The trace width has to be similar to the pad width when connecting the pads and increase if possible some distance from the pad Figure 5 5 Board layout transceiver GND 5 i H 0 i Ee ERR l e 7 vara rir j aa f Ma PA WE 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 Vias should be open on the bottom side to allow enclosed air to expand during the soldering process AIMEL 13 E 8345A AVR 05 11 AIMEL a 5 5 PCB digital GND routing 5 6 PCB GND plane 5 7 Ceramic antenna 5 7 1 Antenna design study 14 Atmel AVR2043 With the Atmel AT86RF231 consider pins 7 12 16 18 and 21 as digital ground pins Digital ground pins are not directly
33. tmel AVR2043 AIMEL Te Typical values contained in this application note are based on simulations and testing 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 The radio extender board is assembled with an Atmel AT86RF231 radio transceiver 1 and two ceramic antennas and demonstrates the unrivaled hardware based antenna diversity feature which significantly improves radio link robustness in harsh environments The radio extender board was designed to interface to Atmel s microcontroller development or evolution platforms The microcontroller platform 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 Test the radio transceivers comprehensive hardware support of the IEEE 802 15 4 standard e Test the radio transceivers enhanced feature set which includes antenna diversity AES high data rate modes and other functions The photograph in Figure 3 1 shows a development and evaluation setup using the REB controller base board 2 in combination with the REB231ED radio extender board Figure 3 1 The REB231ED connected to an REB CBB 8345A AVR 05 1 1 Atmel AVR2043
34. unnnnnnnnnnnnnnnnnnunnnnnnnnnnnnnnnnenunrn 24 1 AbSOlUe Maximum FANGE 4uavsansi e a 24 7 2 Recommended operating range 24 7 35 CUFENE CONSUMPTION Lanes E studs SE a nA 24 8 Abbreviations rnrrnnnnnunnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnennnr 25 e WEE en En E re 26 A 2 Assembly drawing rrrrnnnnnvnnnnnvrnnnevnnnrnvnnnrnnnnrenrnnnennnnrennnnennnssennnnsnnnneennnnsennnn 27 EEE EE JE aaa aa a aa 28 A 4 Radio certification rrrnnrnnnrnnnnvrrnnnnrrrnnnrrnvrnnrrnrnnnrennnnsnrnnnnnesnnnnnssennnnsennnnsssen 29 EET ET EEE E EEEE 30 EVALUATION BOARD KIT IMPORTANT NOTICE rennrnnnnnnnnnrnnnnvnunr 31 9 Table of contents Seet ege eebe Ee EEN EE ke 32 8345A AVR 05 11 T Atmel Corporation Atmel Asia Limited Atmel Munich GmbH Atmel Japan 2325 Orchard Parkway Unit 01 5 amp 16 19F Business Campus 9F Tonetsu Shinkawa Bldg San Jose CA 95131 BEA Tower Milennium City 5 Parkring 4 1 24 8 Shinkawa USA 418 Kwun Tong Road D 85748 Garching b Munich Chou ku Tokyo 104 0033 Tel 1 408 441 0311 Kwun Tong Kowloon GERMANY JAPAN Fax 1 408 487 2600 HONG KONG Tel 49 89 31970 0 Tel 81 3523 3551 www atmel com Tel 852 2245 6100 Fax 49 89 3194621 Fax 81 3523 7581 Fax 852 2722 1369 2010 Atmel Corporation All rights reserved Rev CORP072610 Atmel Atmel logo and combinations thereof AVR and others are registered trademarks of Atmel Corporation or its subsidiaries Other te
35. use 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 the 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 e 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 techni
36. vide a stable 1MHz clock signal with correct logic level to a microcontroller pin with sufficiently Suppressed harmonics CLKM frequencies above 1MHz require a AMEL r NOTE 4 5 RF section 8 Atmel AVR2043 AIMEL Se 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 Channel 26 2480MHZz is affected by the following harmonics 155 x 16MHz or 310 x 8MHz 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 OQ resistor 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 A balun B1 performs the differential to single ended conversion of the RF signal to connect the Atmel AT86RF231 to the RF switch U1 The RF switch is controlled by the radio transceiver output DIG1 and selects one of the two antennas The signal is routed to the ceramic antenna passing a tuning line Solder pads located along the tuning line allow for the optimization of antenna matching without the need for redesigning the REB Detailed information about the antenna diversity feature is given in 1 and 3 Optionally one or two SMA co
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