APPLICATION NOTE AT02876: Atmel REB212BSMA Hardware User Manual Atmel MCU Wireless Introduction This manual describes the REB212BSMA radio extender board, demonstrating ® the high performance at ultra-low power consumption of the Atmel AT86RF212B radio transceiver. Features • High-performance 700/800/900MHz, RF-CMOS AT86RF212B radio transceiver ® ® targeted for ZigBee , IEEE 802.15.4, 6LoWPAN, and ISM Applications – 121dB link budget – Ultra-low current consumption – Ultra-low supply voltage (1.8V to 3.
1 Introduction This manual describes the REB212BSMA radio extender board, demonstrating the high performance at ultra-low power consumption of the Atmel AT86RF212B radio transceiver. Detailed information is given in the individual sections about the board functionality, the board interfaces, and the board design. The REB212BSMA connects directly to the REB controller base board (REB-CBB) [2], or can be used as an RF interface in combination with one of the Atmel microcontroller development platforms.
Figure 3-1 shows a development and evaluation setup using the REB controller base board (REB-CBB) in combination with the REB212BSMA radio extender board; via SMA connector which is assembled with quarter wave whip antenna. Figure 3-1. 4 The REB212BSMA Connected to a REB-CBB Functional Description The block diagram of the REB212BSMA radio extender board is shown in Figure 4-1.
Figure 4-1. REB212BSMA Block Diagram DEVDD JP1 Protectio n GND TP7 TP6 DIG3 DIG4 Balun X2 RSTN RFP IRQ AT86RF212B SLPTR RFN CLKM ID EEPROM EXPAND1 DIG2 SPI XTAL2 TP5 XTAL1 DIG1 4 XTAL REB212BSMA 4.1 Interface Connector The REB212BSMA is equipped with a 2 × 20-pin, 100mil, expansion connector, X1. The pin assignment enables a direct interface to the REB-CBB [2].
Pin# Pin# Function 13 n.c. 14 n.c. 15 n.c. 16 n.c. 17 n.c., optionally XT1 (MCLK) 18 n.c. 19 VCC 20 VCC 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 PB0 (SEL) 31 PD7 (TP1) 32 PD6 (MCLK) 33 PD5 (TP2) 34 PD4 (DIG2) 35 PD3 (TP3) 36 PD2 (open) 37 PD1 (TP4) 38 PD0 (IRQ) 39 GND 40 EE#WP (write protect EEPROM) Note: 4.1.2 Function 1. (1) Possible by retrofitting a 0R assembly.
Pin# Pin# Function 31 PD7 (SLPTR) 32 PD6 (DIG2) 33 PD5 (TP2) 34 PD4 (open) 35 PD3 (TP3) 36 PD2 (IRQ) 37 PD1 (TP4) 38 PD0 (open) 39 GND 40 EE#WP (write protect EEPROM) Note: 4.2 Function 1. Possible by retrofitting a 0R assembly. ID EEPROM To identify the board type by software, an identification (ID) EEPROM (U5) is populated. Information about the board, the node MAC address and production calibration values are stored here.
Address 0x14 Name Feature uint8 Description Board features, coded into seven bits 7 Reserved 6 Reserved 5 External LNA 4 External PA 3 Reserved 2 Diversity 1 Antenna 0 SMA connector 0x15 Cal OSC 16MHz uint8 XTAL calibration value, register XTAL_TRIM 0x16 Cal RC 3.6V uint8 Atmel ATmega1281 internal RC oscillator calibration value @ 3.6V, register OSCCAL 0x17 Cal RC 2.0V uint8 Atmel ATmega1281 internal RC oscillator calibration value @ 2.
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 1MΩ pull-up resistor R21 and the EEPROM standby current. Figure 4-3. 4.4 Power Supply Routing Radio Transceiver Reference Clock The integrated radio transceiver is clocked by a 16MHz reference crystal, Q1. Operating the node according to IEEE 802.15.4 [4], the reference frequency must not exceed a deviation of ±40ppm.
To estimate the effective output power for the SMA connector reference plane, insertion losses of the balun and the transmission line have to be taken into account. Therefore, the SMA connector output power can be up to 1.5dB below the AT86RF212B datasheet value, according to specification of the balun. Insertion loss data for the individual components can be obtained from associated datasheets. Please check the part reference inside the BOM in Appendix A.3.
5.2 Crystal Routing The reference crystal PCB area requires optimization to minimize external interference and to keep any radiation of 16MHz harmonics low. Since the board design incorporates a shield, the crystal housing has been tied hard to ground. This method will minimize the influence of external impairments such as burst and surge. To prevent crosstalk, the crystal is encircled by a ring of ground traces and vias. Special care has to be taken in the area between the IRQ line and the crystal.
Figure 5-3. Board Layout – Transceiver GND Routing 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. 5.
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. The pads where the shield is mounted also need some attention. The shield has to be integrated in the ground planes. Vias, in a short distance to the pads, will ensure a low impedance connection and also close the FR4 substrate as mentioned above.
7 Electrical Characteristics 7.1 Absolute Maximum Ratings Stresses beyond the values listed in Table 7-1 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.
8 References [1] AT86RF212B; Low Power, 700/800/900 MHz Transceiver for ZigBee, IEEE 802.15.4, 6LoWPAN, and ISM Applications; Datasheet; Rev. 42002A–MCU Wireless–04/12; Atmel Corporation. [2] AVR2042: REB Controller Base Board – Hardware User Guide; Application Note; Rev. 8334A-AVR-08/10; Atmel Corporation. [3] AT25010B; SPI Serial EEPROM; Datasheet; Rev. 8707CJ SEEPR 6/11; Atmel Corporation. [4] IEEE Std 802.15.
Appendix A PCB Design Data A.
A.2 Assembly Drawing A.3 Bill of Materials Qty. Designator Description MPN Manufacturer Comment 1 B1 868/900MHz FilterBalun, SMD 1.25x2.0mm 0896FB15A0100 Johanson Technology 0896FB15A0100 4 C31, C32, C35, C36 Ceramic capacitor, SMD 0402, X5R, 6.
Qty. Designator Description MPN Manufacturer Comment 1 Q1 16MHz SX-4025, 4 x 2.5mm SMD 10ppm XTL551150NLE-16.0MH z-9.
Appendix B Radio Certification The REB212BSMA, mounted on a REB controller base board (REB-CBB), has received regulatory approvals for modular devices in the United States and European countries. B.1 United States (FCC) B.1.1 Compliance Statement (Part 15.19) The ATREB212BSMA-EK is certified as Limited modular transmitter with FCC ID VW4A091619. The device complies with Part 15 of the FCC rules.
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.
Appendix C Revision History 20 Doc Rev. Date Comments 42097B 06/2014 "The ATREB212BSMA-EK is certified as Limited modular transmitter with FCC ID VW4A091619" is added in B.1.1. New template. 42097A 04/2013 Initial document release.
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