AVR2038: AT86RF231 Range Extension

Features • High Performance RF-CMOS 2.4GHz Radio Transceiver for IEEE 802.15.4™,

ZigBee®, ZigBee® RF4CE, 6LoWPAN, WirelessHART™ and ISM Applications • Range Extension using High Output Transmitter • Low Current Consumption

TRX_OFF = 0.4mA RX_ON = 12.3mA BUSY_TX = 105mA (at Transmitter Power of +18dBm)

1 Introduction The application note describes the usage, design, and layout of the AT86RF231 Range Extension. An implementation is shown in Figure 1-1. The information provided is intended as a helping hand for hardware designers to make use of the AT86RF231 RF front-end control capabilities.

Figure 1-1. AT86RF231 – Range Extension.

8-bit Microcontrollers Application Note

Rev. 8340A-AVR-10/10

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2 Disclaimer Typical values contained in this application note are based on simulations and testing of individual examples.

3 Introduction The AT86RF231 is a feature rich, low-power 2.4GHz radio transceiver designed for industrial and consumer ZigBee, ZigBee RF4CE, IEEE 802.15.4, 6LoWPAN and high data rate ISM applications.

While these application areas are typically low cost, low power standards, solutions supporting higher transmit output power are occasionally desirable. To simplify the control of an optional external RF front-end, the AT86RF231 provides a differential control pin pair to indicate a transmit operation. A detailed description, how to use and configure the RF front-end control, can be found in the AT86RF231 datasheet [1], section References.

The control of an external RF front-end is done via digital control pins DIG3/DIG4. The function of this pin pair is enabled with register bit PA_EXT_EN (register 0x04, TRX_CTRL_1). While the transmitter is turned off, pin 1 (DIG3) is set to low level and pin 2 (DIG4) to high level. If the radio transceiver starts to transmit, the two pins change their polarity. This differential pin pair can be used to control PA, LNA, and RF switches.

If the AT86RF231 is not in a receive or transmit state, it is recommended to disable register bit PA_EXT_EN (register 0x04, TRX_CTRL_1) to reduce the power consumption or avoid leakage current of external RF switches and other building blocks, especially during SLEEP state. If register bits PA_EXT_EN = 0, output pins DIG3/DIG4 are both at logic low level.

4 Range Extension Board – Overview Figure 4-1 illustrates the setup of the AT86RF231 Range Extension board. It mainly consists of three sections: the microcontroller ATmega1281/V and periphery, the radio transceiver AT86RF231 and the RF front-end with power amplifier and low-pass filtering.

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Figure 4-1. Range Extension Board – Block Diagram.

SPI / Ctrlsignals

AT86RF231

32 kHz 3.68 MHz

ATmega1281

Expansion Connector 1

ID EEPROMLEDsPushbutton

Expansion Connector 2

16 MHz

RF Frontend

The Atmel ATmega1281/V controls the AT86RF231 radio transceiver, and serves as an SPI master. The radio transceiver handles all actions concerning RF modulation/demodulation, signal processing, frame reception and transmission. MAC hardware acceleration functions are implemented in the radio transceiver, too. Further information about the radio transceiver and the microcontroller are available in the appropriate datasheets, refer to [1] and [2].

The RF front-end incorporates signal amplification and filtering of the transmit signal. The degree of filtering depends on operating conditions as well as regional aspects. Switching between reception and transmission is directly controlled by the radio transceiver. This allows the unlimited use of the radio transceiver MAC acceleration modes RX_AACK and TX_ARET, see [1], and reduces the microcontroller interaction significantly. The usage of a low-noise amplifier (LNA) is not demonstrated in this application note, even if it is possible by reusing already existing control signals.

All components are placed on one side of a four-layer, 1.5mm standard FR4 printed circuit board, giving a low cost manufacturing solution.

A schematic of the RCB can be found in Appendix A.1 - Schematic.

4.1 Power Supply The board is powered by a single supply voltage in the range of 2.7V to 3.6V, which makes it possible to be powered by two 1.5V cells. Optionally the power can be supplied externally. All semiconductors are supplied by this power, reducing component count and power losses of voltage converters.

Battery power

For autonomous operation the AT86RF231 Range Extension board can be powered by two AAA batteries that are held by the battery clip on the back of the board. Use power switch SW1 to manually switch on/off the board.

External power

When used as a daughter board in a more complex system, the board can be powered through the expansion connectors. For pin mapping see Table 4-2. In this case the power switch has to be in OFF position to avoid unintentionally charging of the batteries, if they are applied.

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4.2 Microcontroller The Atmel ATmega1281/V is a low-power 8-bit microcontroller based on the AVR® enhanced RISC architecture. The non-volatile flash program memory of 128kB and 8kB of internal SRAM, supported by a rich set of peripheral units, makes it suitable for a full function sensor network node.

The microcontroller is capable of operating as a PAN-coordinator, a full function device (FFD) as well as a reduced function device (RFD), as defined by IEEE802.15.4 [3]. However, the AT86RF231 Range Extension board is not limited to this and can be programmed to operate other standards or ISM applications, too.

4.3 RF Section The radio transceiver AT86RF231 contains all RF and BB critical components necessary to transmit and receive signals according to IEEE802.15.4 or proprietary ISM data rates.

In this application note, the RF front-end is used mainly to demonstrate the RX/TX indicator usage in order to control a power amplifier. A balun B1 performs the differential to single ended conversion to connect the AT86RF231 to the RF front-end. Two SPDT switches separate receive and transmit paths. The transmit path incorporates a power amplifier (PA) and low-pass filter (LPF). Both RF switches, and PA are directly controlled by the radio transceiver, for details refer to [1] in section References. Additional low pass filtering (L4/5, C28/29) between RX/TX switch U7 and antenna may be required to further suppress harmonics caused by the limited isolation of the 2/1 RF switch. The amount of harmonic filtering has to be aligned to regional requirements. For instance, operating the device according to ETSI EN 300 228 [6] or ARIB STD-T66 [7], the LPF can be removed. Furthermore, it has to be noted that ETSI EN 300 228 limits the transmitter output power to +10dBm/MHz ERP. The transmitter output power for boards operating under ARIB STD-T66 depends on the data rate selected.

Note - any modification in the PA RF path, including the LPF, requires a review of the RF front-end circuitry to ensure an optimum operating point of the PA. Any modification of components, PCB layout and shielding influences the performance of the circuitry.

A separate switched supply VDD_SW for the RF front-end, see Figure A. 1-2, disconnects it from the main radio transceiver power supply VDD in case of no active transceiver operation. This ensures the lowest possible current consumption for all other operating modes. If this is not needed, IC1B and R16 are not required; VDD_SW can be connected to VDD via L12.

An antenna has to be connected to the SMA connector for proper operation.

4.4 Clock Sources Radio Transceiver

The radio transceiver is clocked by the 16MHz reference crystal Q1. The 2.4GHz modulated signal is derived from this clock. Operating the node according to IEEE802.15.4 [3] the reference frequency should 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.

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The radio transceiver reference crystal Q1 is isolated from fast switching digital signals and surrounded by the ground plane to minimize disturbances of the oscillation.

The AT86RF231 Range Extension board uses a SIWARD crystal SX4025 with two load capacitors of 10pF. To compensate fabrication and environment variations the frequency can be tuned with the transceiver register “XOSC_CTRL (0x12)”, for more detailed information refer to [1], section References. An initial tuning is done during fabrication and stored in the onboard EEPROM, also carrying the board ID, see section 4.6.

Microcontroller

There are various clock source options for the microcontroller Atmel ATmega1281/V.

• 8MHz calibrated internal RC oscillator • 128kHz internal RC oscillator • 3.6872MHz ceramic resonator • CLKM 1..16MHz (radio transceiver clock) The 8MHz calibrated internal RC oscillator is used as the default clocking. The CLKM signal, generated by the transceiver, is connected to T1 (PD6) of the ATmega1281V and can be used as a symbol synchronous counter as well as a reference clock to calibrate the internal RC oscillator. Optionally, the microcontroller can be clocked directly from the CLKM signal, for this purpose the 0Ω resistor R105 has to be soldered to R102 and R104 has to be mounted. In this configuration Q101 and C104/5 are not required.

A 32kHz crystal is connected to the AVR pins (TOSC1, TOSC2) to be used as a low power real time clock. The connection of the SLP_TR pin of the radio transceiver to the OC2A pin (PB4) of the ATmega1281/V makes it possible to wake up both the microcontroller and the radio transceiver simultaneously from a Timer 2 Output Compare Match event.

This operation mode saves valuable time in a cycled sleep/wakeup network scenario.

4.5 On-Board Peripherals For simple applications, debugging purposes or just to deliver status information, a basic user interface is provided directly on the board, consisting of three LED’s and a pushbutton connected to Port E (PE2…PE4 and PE5).

4.6 ID EEPROM To identify the board type by software, an optional identification EEPROM is populated. Information about the board, the node MAC address and production calibration values are stored here. An Atmel AT25010A with 128 x 8 bit organization and SPI interface is used because of its small package, and low voltage and low power operation.

For interfacing the EEPROM, the SPI bus is shared with the transceiver. The select signal for each of the SPI slave (EEPROM, radio transceiver) is decoded with the reset line RSTN of the transceiver. Therefore, the EEPROM is addressed when the radio transceiver is held in reset (RSTN = 0), see Figure 4-2.

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Figure 4-2. EEPROM Access Decoding Logic.

>1

>1

PB5 (RSTN)

SEL#

RSTN

SPIPB1..3 (SPI)

Transceiver AT86RF231

On-BoardEEPROM

PB0 (SEL)

/RST

/SEL

#CS

The EEPROM data is written during board production test. A unique serial number; the MAC address(1) as well as calibration values, is stored. These can be used to optimize system performance.

Final products do not require this external ID EEPROM. All data can be stored directly in the microcontroller internal EEPROM. The following table gives the data structure of the EEPROM.

Table 4-1. ID EEPROM Mapping. Address Name Type Description 0x40 MAC address uint64 MAC address (1) for the 802.15.4 node, little

endian byte order

0x48 Serial Number uint64 Board serial number, little endian byte order

0x50 Board Family uint8 Internal board family identifier

0x51 Revision uint8[3] Board revision number ##.##.##

0x54 Feature uint8 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 0x55 Cal OSC

16MHz uint8 RF231 XTAL calibration value, register

“XTAL_TRIM”

0x56 Cal RC 3.6V uint8 AVR internal RC oscillator calibration value @ 3.6V, register “OSCCAL”

0x57 Cal RC 2.0V uint8 AVR internal RC oscillator calibration value @ 2.0V, register “OSCCAL”

0x58 Antenna Gain int8 Antenna gain [1/10dBi]

0x60 Board Name char[30] Textual board description

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Address Name Type Description 0x7E CRC uint16 16 Bit CRC checksum, standard ITU-T generator

polynomial G16(x) = x16 + x12 + x5 + 1

Note: 1. MAC addresses used for this package are Atmel property. The use of these MAC addresses for development purposes is permitted.

4.7 External Peripherals The RCB is equipped with two 50 mil connectors to place the board on a variety of expansion boards. The connectors provide access to all spare Atmel ATmega1281/V pins, including USART, TWI, ADC, PWM and external memory pins.

The detailed pin mapping is shown in Table 4-2.

Table 4-2. Expansion Connector Mapping. EXT0 EXT1

Pin# Function Pin# Function Pin# Function Pin# Function 1 PB6 2 PB7 1 PB1 (SCK) 2 GND

3 #RESET 4 VCC 3 PE7 4 PE6

5 GND 6 XTAL2 5 PE5 6 PE4

7 XTAL1 8 GND 7 PE3 8 PE2

9 PD0 (SCL) 10 PD1 (SDA) 9 PE1 (PDO) 10 PE0 (PDI)

11 PD2 (RXD1) 12 PD3 (TXD1) 11 AGND 12 AREF

13 PD4 14 PD5 13 PF0 14 PF1

15 PD6 (CLKM) 16 PD7 15 PF2 16 PF3

17 PG0 (#WR) 18 PG1 (#RD) 17 PF4 (TCK) 18 PF5 (TMS)

19 GND 20 GND 19 PF6 (TDO) 20 PF7 (TDI)

21 PC0 22 PC1 21 Vcc 22 GND

23 PC2 24 PC3 23 PA0 24 PA1

25 PC4 26 PC5 25 PA2 26 PA3

27 PC6 28 PC7 27 PA4 28 PA5

29 GND 30 PG2 (ALE) 29 PA6 30 PA7

5 Programming This RCB type of board provides all required programming interfaces through the two 50 mil connectors. Using an appropriate expansion board the interfaces are available as 100 mil connectors to connect for instances to a JTAGICE mkII.

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6 Electrical Characteristics

6.1 Absolute Maximum Ratings Absolute maximum ratings are dependent on the individual parts and their usage within the final design. For details about these parameters, refer to individual datasheets of the components used.

6.2 Recommended Operating Range Table 6-1.Operating Range. No. Symbol Parameter Condition Min. Typ. Max. Units

6.2.1 TOP Operating temperature range (1) -20 +70 °C

6.2.2 fRF Operating frequency range 2400 2483.5 MHz

6.2.3 VCC Supply voltage 2.7 (2) 3.0 3.6 V

Notes: 1. Operating temperature range is limited by crystal only, other important components covering a range of -40…+85°C. For details refer individual datasheets.

2. Minimum value set by power amplifier specification. A lower value of the minimum supply voltage will affect the TX output power.

6.3 General RF Specifications Test Conditions (unless otherwise stated):

VDD = 3.0V, fRF = 2.45GHz, TOP = 25°C

Table 6-2.RF Specifications. No. Symbol Parameter Condition Min. Typ. Max. Units

6.3.1 fRF Frequency range As specified in [3] 2405 2480 MHz

6.3.2 fCH Channel spacing As specified in [3] 5 MHz

6.3.3 fHDR Header bit rate (SHR, PHR) As specified in [3] 250 kb/s

6.3.4 fPSDU_Sym PSDU symbol rate As specified in [3] 62.5 ks/s

6.3.5 fPSDU_Bit PSDU bit rate As specified in [3] OQPSK_DATA_RATE = 1 OQPSK_DATA_RATE = 2 OQPSK_DATA_RATE = 3

250 500

1000 2000

kb/s kb/s kb/s kb/s

6.3.6 fCHIP Chip rate As specified in [3] 2000 kchip/s

6.3.7 fXTAL Crystal oscillator frequency Reference oscillator (XTAL) 16 MHz

6.3.8 fXTAL_ACC XTAL frequency accuracy -40 (1) +40 ppm

6.3.9 tXTAL XTAL settling time Leaving SLEEP state to clock available at pin 17 (CLKM)

330 1000 µs

6.3.10 B20dB 20dB bandwidth 2.8 MHz

Note: 1. A reference frequency accuracy of ±40ppm is required by [3].

6.4 Transmitter Characteristics Test Conditions (unless otherwise stated):

VCC = 3.0V, fRF = 2.45GHz, TOP = 25°C

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Table 6-3.Transmitter Characteristics. No. Symbol Parameter Condition Min. Typ. Max. Units

6.4.1 PTX TX Output power Maximum configurable TX output power value (2) Register bit TX_PWR = 0

-4 (3) +18 (1) +21 (3) dBm

6.4.2 PRANGE Output power range 16 steps, configurable in register 0x05 (PHY_TX_PWR)

15 dB

6.4.3 PACC Output power tolerance ±3 dB

6.4.4 EVM 8 % rms

6.4.5 PHARM Harmonics (FCC) (1) 2nd harmonic 3rd harmonic

Pout = Pmax CW, no modulation

-42 -50

dBm dBm

6.4.6 PSPUR Spurious Emissions 30 – ≤1000MHz >1 – 12.75GHz 1.8 – 1.9GHz 5.15 – 5.3GHz

Complies with (1) EN 300 328/440, FCC-CFR-47 part 15, ARIB STD-66, RSS-210

-36 -30 -47 -47

dBm dBm dBm dBm

Notes: 1. Note - the operation of devices using a high output power has to follow rules of the local regulatory bodies, like FCC [5], ETSI [6], ARIB [7] or other authorities.

2. According to EN 300 328 and STD-T66 (partly) the TX output power is limited to 10mW/MHz. The low-pass filter consisting of L4/5 and C28/29 is not required.

3. Min. and Max. are typical values for minimum output power at lowest supply voltage or maximum output power at maximum supply voltage, respectively.

6.5 Current Consumption Specifications Test Conditions (unless otherwise stated) (1) (2)

VDD = 3.0V, fRF = 2.45GHz, TOP = 25°C, MCU off

Table 6-4.Current Consumption Specifications. No. Symbol Parameter Condition Min. Typ. Max. Units

6.5.1 IBUSY_TX Supply current transmit state PTX,max = +18dBm PTX,min = +4dBm

105 36

mA mA

6.5.2 IRX_ON Supply current RX_ON state RX_ON state – high input level (3) 10.3 mA

6.5.3 IRX_ON Supply current RX_ON state RX_ON state – high sensitivity 12.3 mA

6.5.4 IRX_ON_P Supply current RX_ON state RX_ON state, with register setting RX_PDT_LEVEL > 0

11.8 mA

6.5.5 IPLL_ON Supply current PLL_ON state PLL_ON state 5.6 mA

6.5.6 ITRX_OFF Supply current TRX_OFF state TRX_OFF state 0.4 mA

6.5.7 ISLEEP Supply current SLEEP state SLEEP state 0.02 μA

Notes: 1. Current consumption figures does not include microcontroller. 2. Current consumption for all operating modes is reduced at lower VDD. 3. Current consumption for operating modes other than transmit are similar to

radio transceiver only without RF front-end, see [1].

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7 Typical Characteristics

7.1 TX Supply Current The following charts each show a typical behavior of the AT86RF231 Range Extension Boards. These figures are examples only and not tested during manufacturing.

Power consumption of the microcontroller required to program the radio transceiver as well as power consumption of the LED’s are not included in the measurement results.

The current consumption is a function of several factors such as: operating voltage, operating frequency, loading of I/O pins, switching rate of I/O pins, and ambient temperature. The dominating factors are operating voltage and ambient temperature.

If possible, measurement results are not affected by current drawn from I/O pins. Register, SRAM or Frame Buffer read or write accesses are not performed during current consumption measurements.

7.1.1 TX_BUSY state

Figure 7-1.Current Consumption vs. TX_PWR.

0

20

40

60

80

100

120

140

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

TX_PWR (Register Value)

PA +

PH

Y C

urre

nt C

onsu

mpt

ion

[mA

]

3.6 V3.3 V3.0V2.5 V

Ch22

Note: Setting of AT86RF231 register bits TX_PWR are according to [1]. The highest radio transceiver output power of +3dBm is achieved by setting register bits TX_PWR = 0, and the lowest radio transceiver TX output power of -17dBm with TX_PWR = 0, respectively. For further details refer to [1], section References, and see Figure 7-4.

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Figure 7-2. Current Consumption vs. TX Output Power.

10

30

50

70

90

110

130

150

-6 -4 -2 0 2 4 6 8 10 12 14 16 18 20 22

TX output Power [dBm]

PA +

PH

Y C

urre

nt C

onsu

mpt

ion

[mA

] 3.6 V3.3 V3.0 V2.5 V

Ch22

Figure 7-3. Current Consumption vs. Channel (TX_PWR = 0).

60

70

80

90

100

110

120

130

140

150

10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27

Channel

PA +

PH

Y C

urre

nt C

onsu

mpt

ion

[mA

]

3.6 V3.3 V3.0 V2.5 V

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7.2 TX Performance

7.2.1 TX Output Power

Figure 7-4. TX Output Power vs. TX_PWR.

-6-4-202468

10121416182022

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

TX_PWR (Register Value)

RC

B23

1LPA

TX

Pout

[dB

m]

-23-21-19-17-15-13-11-9-7-5-3-1135

AT8

6RF2

31 T

X Po

ut [d

Bm

]

3.6 V

3.3 V

3.0V

2.5 V

AT86RF231

Ch18

7.2.2 TX Output Power vs. IEEE802.15.4 Channel

Figure 7-5. TX Output Power vs. Channel (TX_PWR = 0).

12

13

14

15

16

17

18

19

20

21

22

10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27

Channel

TX O

utpu

t Pow

er [d

Bm

]

3.6 V3.3 V3.0V2.5 V

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7.2.3 TX Modulation Accuracy (EVM)

Figure 7-6. Error Vector Magnitude vs. TX Output Power.

6

6,5

7

7,5

8

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

TX_PWR (Register Value)

EVM

[%]

3.6 V

3.0 V

2.5 V

Ch19

Figure 7-7. Error Vector Magnitude vs. IEEE802.15.4 Channel (TX_PWR = 0).

5

6

7

8

9

10

10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27

Channel

EVM

[%]

3.6 V

3.0 V

2.5 V

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7.2.4 RF Front-End Transmit Gain

Figure 7-8. RF Front-End Overall Transmit Gain.

6789

1011121314151617181920212223

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

TX_PWR (Register Value)

RF

Fron

t-End

Tra

nsm

it G

ain

[dB

]

3.6 V

3.3 V

3.0V

2.5 V

Ch18

7.2.5 Harmonics

Figure 7-9. TX Pout and Harmonics vs. IEEE802.15.4 Channel (TX_PWR = 0)

12

13

14

15

16

17

18

19

20

21

22

10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27

Channel

Fund

amen

tal O

utpu

t Pow

er [d

Bm

]

-60

-58

-56

-54

-52

-50

-48

-46

-44

-42

-40

Har

mon

ic O

utpu

t Pow

er [d

Bm

]

f02 f03 f04 f0

Note: Harmonic measurement results shown in this paper are derived using CW signals without modulation, and therefore illustrating a worst case scenario. Applying normal TX test mode operation using IEEE802.15.4 modulated signals, harmonic power is further reduced due to the relation of a limited measurement detector bandwidth and a wide modulation bandwidth.

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7.2.6 Spurious Emissions – FCC

Figure 7-10. FCC Band Edge Spurious Emissions (conducted).

PSD

-60

-50

-40

-30

-20

-10

0

10

20

30

40

2200 2250 2300 2350 2400 2450 2500 2550 2600 2650 2700

Frequency [MHz]

Po

wer

[dB

m]

RBW = 1 MHz, VBW = 10Hz

FCC part 15.247 limit

Figure 7-11. FCC Band Edge Spurious Emissions (conducted), Lower Band Edge.

PSD - Lower Channels

-60

-50

-40

-30

-20

-10

0

10

20

30

40

2385 2390 2395 2400 2405 2410 2415 2420

Frequency [MHz]

Po

wer

[dB

m]

RBW = 1 MHz, VBW = 10Hz

FCC part 15.247 limit

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Figure 7-12. FCC Band Edge Spurious Emissions (conducted), Upper Band Edge.

PSD - Higher Channels

-60

-50

-40

-30

-20

-10

0

10

20

30

40

2460 2465 2470 2475 2480 2485 2490 2495 2500

Frequency [MHz]

Po

wer

[dB

m]

RBW = 1 MHz, VBW = 10Hz

FCC part 15.247 limit

Note: Operating the AT86RF231 Range Extension in the United States, FCC regulates the usage of such devices intended for unlicensed operation in the 2.4GHz ISM band [5]. A summary is given in IEEE802.15.4-2006 [3]; refer to the informative Annex F, IEEE 802.15.4 regulatory requirements. Harmonic requirements of Section 15.247 of FCC CFR47 are easily achieved using the low pass filter consisting of L4/5 and C28/29, even if 2nd and 3rd harmonics fall into restricted bands. Most critical areas are spurious emissions at lower and upper band edges. Especially the upper band edge requirement is hard to achieve for devices transmitting at higher output power. According to FCC Part 15.247, an IEEE802.15.4 compliant device using DSSS modulation is allowed to transmit up to +30dBm (conducted). Referring to Figure 7-12, out-of band power from certain channels violates the requirements of FCC 15.247 in the restricted bands up to 2390MHz and starting from 2483.5MHz. To achieve this requirement, the output power of the affected channels has to be reduced and/or a duty cycle has to be introduced. To investigate spurious emissions for frequencies above 1GHz, FCC CFR47 specifies peak and average limits in combination with specific detectors. The averaging limit is related to a 100ms reference period. The application of the average detector allows higher fundamental if the active on-air transmit time is less than the reference period. A relaxation factor can be calculated according to: min20 dB; 20log((TX on-air time)/100ms) This factor may be applied to the spurious emissions. In other words, if spurious emissions are above the average limit, duty cycle operation has to be introduced to fulfill specification. However, this can be applied to an average reading only, peak limits are to be fulfilled without exceptions. A peak limit violation requires TX output power back-off for the affected channel.

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In this example, assuming conducted measurements and taking no band-edge spur margin into account, a duty cycle and/or back-off is required for a few channels. The required duty cycle and/or back-off depend on the final implementation, in detail the achieved TX output power. Conducted band-edge measurements, resulting in a certain duty-cycle and/or back-off requirements as shown in Figure 7-13, are derived following FCC recommendations published in FCC public notice DA00-705, also known as marker delta method.

Figure 7-13. AT86RF231 Range Extension Duty-Cycle and PA Back-Off.

13

14

15

16

17

18

19

20

21

22

23

10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27

Channel

Max

imum

TX

Out

put P

ower

[dB

m]

0

10

20

30

40

50

60

70

80

90

100

Max

imum

Dut

y C

ycle

[%]

3.6 V3.0 V2.7 V3.6 V (DC)3.0 V (DC)2.7 V (DC)

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Appendix A – Design

A.1 - Schematic

Figure A.1-1. RCB231LPA – RF Front-End Section.

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Figure A. 1-2. RCB231LPA – Transceiver Section.

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Figure A. 1-3. RCB231LPA – MCU Section.

13 2

Q10

1C

STC

C3.

68G

-A

C10

110

0n

C10

210

0n

C10

310

0n

C10

410

pC

105

10p

C10

622

pC

107

22p

R10

1

10k

12

34

56

78

910

1112

1314

1516

1718

1920

2122

2324

2526

2728

2930

EXT0

SFM

-115

-L2-

S-D

-LC

12

34

56

78

910

1112

1314

1516

1718

1920

2122

2324

2526

2728

2930

EXT1

SFM

-115

-L2-

S-D

-LC

D1

rot

D2

rot

D3

rot

T1Kn

itter

TSS

31N

R10

2N

C

R4

470

R5

470

R6

470

Batt1

AAAx

2

C10

810

0n

L101

Wue

rth74

2792

66

VCC

VCC

VCC

R10

3N

C

R10

4N

C

SW1

Eao0

9.10

201.

02

(32k

Hz)

R10

50R

VCC

C10

910

n

L102

Wue

rth74

2792

66

VCC

C11

010

0n

L103

Wue

rth74

2792

66

PG5(

OC

0B)

1

PE0(

RXD

0/PC

INT8

/PD

I)2

PE1(

TXD

0/PD

O)

3

PE2(

XCK0

/AIN

0)4

PE3(

OC

3A/A

IN1)

5

PE4(

OC

3B/IN

T4)

6

PE5(

OC

3C/IN

T5)

7

PE6(

T3/IN

T6)

8

PE7(

ICP3

/CLK

O/IN

T7)

9

PB0(

/SS/

PCIN

T0)

10

PB1(

SCK/

PCIN

T1)

11

PB2(

MO

SI/P

CIN

T2)

12

PB3(

MIS

O/P

CIN

T3)

13

PB4(

OC

2A/P

CIN

T4)

14

PB5(

OC

1A/P

CIN

T5)

15

PB6(

OC

1B/P

CIN

T6)

16

PB7(OC0A/OC1C/PCINT7)17

PG3(TOSC2)18

PG4(TOSC1)19

RESET 20

Vcc 21

GND22

XTAL223

XTAL124

PD0(SCL/INT0)25

PD1(SDA/INT1)26

PD2(RXD1/INT2)27

PD3(TXD1/INT3)28

PD4(ICP1)29

PD5(XCK1)30

PD6(T1)31

PD7(T0)32

PG0(

/WR

)33

PG1(

/RD

)34

PC0(

A8)

35

PC1(

A9)

36

PC2(

A10)

37

PC3(

A11)

38

PC4(

A12)

39

PC5(

A13)

40

PC6(

A14)

41

PC7(

A15)

42

PG2(

ALE)

43

PA7(

AD7)

44

PA6(

AD6)

45

PA5(

AD5)

46

PA4(

AD4)

47

PA3(

AD3)

48

PA2(AD2)49

PA1(AD1)50

PA0(AD0)51

Vcc52

GND53

PF7(ADC7/TDI)54

PF6(ADC6/TDO)55

PF5(ADC5/TMS)56

PF4(ADC4/TCK)57

PF3(ADC3)58

PF2(ADC2)59

PF1(ADC1)60

PF0(ADC0)61

AREF62

AGND63

AVcc64

GND65

U5

ATM

EGA_

1281

(RS-

204-

7871

)

Q10

2

CFP

X-15

7

AVcc

AREF

Plug

1AM

P 2-

3316

77-2

Plug

2AM

P 2-

3316

77-2

A2

K1

D4

BAS1

40W

VCC

PE7

PE5

PE3

PE0

PE2

PE4

PE6

AREF

PF0

PF1

PF2

PF3

PF4

PF5

PF6

PF7

PA0

PA1

PA2

PA3

PA4

PA5

PA6

PA7

PB1

PE1

PE0

PE1

PE3

PE6

PE2

PE4

PE5

PE7

PA1

PB1

PA0

PA2

PA3

PA4

PA5

PA6

PA7

PF0

PF1

PF2

PF3

PF4

PF5

PF6

PF7

AGND

AGN

D

#RES

ET

XTAL

1XT

AL2

PB6

PB7

PD0

PD2

PD4

PD6

PG0

PC0

PC2

PC4

PC6

PD1

PD3

PD5

PD7

PG1

PC1

PC3

PC5

PC7

PG2

PC0

PC1

PC2

PC3

PC4

PC5

PC6

PC7

PG2

PG0

PG1

XTAL

1

XTAL

2PD4

PD0

PD5

PD6

PD7

PD6

XTAL

_1

XTAL

_2

#RESET

#RES

ET

PB0

PB2

PB3

PB4

PB5

PB6

PD4

PB7

XTAL

_1

VCC

PB1

PB3

PB2

PB0

VCC

VCC

PB5

PB4

PD0

PD1

PD2

PD3

VCC

AREF

AGN

D

AVcc

RST

N

SLP_

TR

CLK

M

SCK

MIS

O

MO

SI

SEL

IRQ

ICP1

Tran

scei

ver

Tran

scei

ver S

ectio

n

VDD

AVR2038

21

8340A-AVR-10/10

A.2 – Assembly Drawing

Figure A. 2-4. RCB231LPA – Assembly Drawing.

22 AVR2038 8340A-AVR-10/10

A.3 – Bill of Material (BoM) Quantity Comment Description Designator Footprint

1 WE_748421245 Balun Wuert 748421245 B1 BALUN08051 AAAx2 Battery Batt1 BH-421-31 47uF/6V Electrolytic Capacitor C1 TANTAL_C

14 22p Capacitor C3, C8, C15, C17, C19, C20, C21, C23, C24, C25, C26, C27, C106, C107

0402

4 1uF Capacitor C4, C11, C12, C14 06038 100n Capacitor C5, C6, C7, C101, C102,

C103, C108, C1100402

4 10p Capacitor C9, C10, C104, C105 04022 1nF Capacitor C13, C16 04021 1p5 Capacitor C22 04021 0p5 Capacitor C28 04021 0p5 Capacitor C29 04021 10n Capacitor C109 04023 rot D1, D2, D3 LED06031 BAS140W Schottky Diode D4 SOD-3231 SFM-115-L2-S-D-LC Connector 15x2-pol. EXT0 SFM151 SFM-115-L2-S-D-LC EXT1 SFM151 2450LP14B100S F1 0603-61 Si1563DH MOSFET IC1 SOT-SC70/6-Dual Co1 39nH Inductor L1 06031 1,5nH Inductor L2 04021 4.7nH Inductor L3 04022 4.7nH Inductor L4, L5 06034 Wuerth74279266 L12, L101, L102, L103 06031 Logo 1 LG1 LOGO solder1 Logo 2 LG2 LOGO solder1 Nut NT11 M2,5x8 NT22 AMP 2-331677-2 Plug1, Plug21 16MHz / CL=10pF Crystal Siward A207-011 Q1 XTAL_4X2_5_small1 CSTCC3.68G-A Q101 CSTCC1 CFPX-157 Crystal Q102 CFPX2 1M Resistor R1, R2 04023 n.b. Resistor R3, R8, R11 04024 470 Resistor R4, R5, R6, R7 04023 0R Resistor R9, R10, R105 04024 1k Resistor R12, R13, R14, R15 04021 100k Resistor R16 04022 10k Resistor R17, R101 04023 NC Resistor R102, R103, R104 04021 Shield_BMIS SH1 LT08AD4303F1 Eao09.10201.02 Switch 1W SW1 EAO1XUM1 Knitter TSS31N Pushbutton 1P T1 Taster_ITT1 AT86RF231 802.15.4 2.4GHz TRX U1 MLF-321 NC7WV04 2x 2 Input Inverter U2 SC-70-61 AT25010A U3 Mini-Map-81 NC7WP32 2x 2 Input OR Gatter U4 SC-70-81 ATMEGA_1281 8-bit AVR uC U5 MLF64-M21 uPG2314T5N U6 TSON-62 AS222-92 U7, U8 SC-70/61 SMA 50Ohm X1 SMA_BU

AVR2038

23

8340A-AVR-10/10

Appendix B – Abbreviation ADC - Analog-to-digital converter

BB - Base Band

CRC - Cyclic redundancy check

FCC - Federal Communication Commission

FFD - Full Functional Device

ISM - Industrial, Scientific, and Medical

LNA - Low Noise Amplifier

MAC - Medium Access Control

PA - Power Amplifier

PHR - PHY Header

PHY - Physical Layer

PSDU - PHY Service Data Unit

RCB - Radio Controller Board

PWM - Pulse Width Modulation

RF - Radio Frequency

RFD - Reduced Functional Device

RX - Receiver

TWI - 2-wire Serial Interface

TX - Transmitter

USART - Universal Asynchronous Receiver Transmitter

24 AVR2038 8340A-AVR-10/10

Appendix C – 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 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 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 © 2010, Atmel Corporation

AVR2038

25

8340A-AVR-10/10

References [1] AT86RF231; Low Power, 2.4 GHz Transceiver for ZigBee, IEEE 802.15.4,

6LoWPAN, RF4CE, SP100, WirelessHART and ISM Applications; Datasheet; Rev. 8111B-MCU Wireless-02/09; Atmel Corporation.

[2] ATmega1281/V; 8-bit Microcontroller with 128K Bytes In-System Programmable Flash; Datasheet; Rev. 2549L–AVR–08/07; Atmel Corporation.

[3] 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).

[4] AT86RF231; Software Programming Model; Rev.2.0; Atmel Corporation.

[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 2.4 GHz 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.

8340A-AVR-10/10

Disclaimer

Atmel Corporation 2325 Orchard Parkway San Jose, CA 95131 USA Tel: (+1)(408) 441-0311 Fax: (+1)(408) 487-2600 www.atmel.com

Atmel Asia Limited Unit 01-5 & 16, 19F BEA Tower, Milennium City 5 418 Kwun Tong Road Kwun Tong, Kowloon HONG KONG Tel: (+852) 2245-6100 Fax: (+852) 2722-1369

Atmel Munich GmbH Business Campus Parkring 4 D-85748 Garching b. Munich GERMANY Tel: (+49) 89-31970-0 Fax: (+49) 89-3194621

Atmel Japan 9F, Tonetsu Shinkawa Bldg. 1-24-8 Shinkawa Chou-ku, Tokyo 104-0033 JAPAN Tel: (+81) 3523-3551 Fax: (+81) 3523-7581

© 2010 Atmel Corporation. All rights reserved. / Rev.: CORP072610

Atmel®, logo and combinations thereof, and others are registered 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, 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, or warranted for use as components in applications intended to support or sustain life.