AVR2038: AT86RF231 Range Extension 8-bit ... - Atmel Corporation

Features
AVR2038: AT86RF231 Range Extension
• 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

2 Disclaimer
3 Introduction
4 Range Extension Board – Overview
2 AVR2038
Typical values contained in this application note are based on simulations and testing
of individual examples.
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.
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.
8340A-AVR-10/10

4.1 Power Supply
8340A-AVR-10/10
Figure 4-1. Range Extension Board – Block Diagram.
Expansion
Connector 1
Expansion
Connector 2
Pushbutton
32 kHz 3.68 MHz
ATmega1281
LEDs
SPI / Ctrl
signals
ID
EEPROM
16 MHz
AT86RF231
AVR2038
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.
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.
3

4.2 Microcontroller
4.3 RF Section
4.4 Clock Sources
4 AVR2038
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.
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.
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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8340A-AVR-10/10
AVR2038
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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6 AVR2038
Figure 4-2. EEPROM Access Decoding Logic.
PB5 (RSTN)
PB0 (SEL)
PB1..3 (SPI)
>1
>1
RSTN
SEL#
SPI
/RST
/SEL
#CS
Transceiver
AT86RF231
On-Board
EEPROM
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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4.7 External Peripherals
5 Programming
8340A-AVR-10/10
Address Name Type Description
AVR2038
0x7E CRC uint16 16 Bit CRC checksum, standard ITU-T generator
polynomial G16(x) = x 16 + x 12 + x 5 + 1
Note: 1. MAC addresses used for this package are Atmel property. The use of these
MAC addresses for development purposes is permitted.
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
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.
7

6 Electrical Characteristics
6.1 Absolute Maximum Ratings
6.2 Recommended Operating Range
8 AVR2038
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.
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]
250
kb/s
OQPSK_DATA_RATE = 1
500
kb/s
OQPSK_DATA_RATE = 2
1000
kb/s
OQPSK_DATA_RATE = 3
2000
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
6.4 Transmitter Characteristics
Note: 1. A reference frequency accuracy of ±40ppm is required by [3].
Test Conditions (unless otherwise stated):
VCC = 3.0V, fRF = 2.45GHz, TOP = 25°C
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8340A-AVR-10/10
AVR2038
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)
2 nd harmonic
3 rd Pout = Pmax
CW, no modulation
-42
dBm
harmonic
-50
dBm
6.4.6 PSPUR Spurious Emissions
Complies with
30 – ≤1000MHz
>1 – 12.75GHz
1.8 – 1.9GHz
5.15 – 5.3GHz
(1)
EN 300 328/440,
-36
dBm
FCC-CFR-47 part 15,
-30
dBm
ARIB STD-66, RSS-210
-47
dBm
-47
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
(1) (2)
Test Conditions (unless otherwise stated)
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
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].
105
36
mA
mA
9

7 Typical Characteristics
7.1 TX Supply Current
7.1.1 TX_BUSY state
10 AVR2038
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.
Figure 7-1.Current Consumption vs. TX_PWR.
PA + PHY Current Consumption [mA]
140
120
100
80
60
40
20
0
3.6 V
3.3 V
3.0V
2.5 V
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
TX_PWR (Register Value)
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.
Ch22
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8340A-AVR-10/10
Figure 7-2. Current Consumption vs. TX Output Power.
PA + PHY Current Consumption [mA]
150
130
110
90
70
50
30
3.6 V
3.3 V
3.0 V
2.5 V
AVR2038
10
-6 -4 -2 0 2 4 6 8 10 12 14 16 18 20 22
TX output Power [dBm]
Figure 7-3. Current Consumption vs. Channel (TX_PWR = 0).
PA + PHY Current Consumption [mA]
150
140
130
120
110
100
90
80
70
60
10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27
Channel
3.6 V
3.3 V
3.0 V
2.5 V
Ch22
11

7.2 TX Performance
7.2.1 TX Output Power
12 AVR2038
Figure 7-4. TX Output Power vs. TX_PWR.
RCB231LPA TX Pout [dBm]
7.2.2 TX Output Power vs. IEEE802.15.4 Channel
22
20
18
16
14
12
10
8
6
4
2
0
-2
-4
3.6 V
3.3 V
3.0V
2.5 V
AT86RF231
-6
-23
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
TX_PWR (Register Value)
Figure 7-5. TX Output Power vs. Channel (TX_PWR = 0).
TX Output Power [dBm]
22
21
20
19
18
17
16
15
14
13
3.6 V
3.3 V
3.0V
2.5 V
12
10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27
Channel
Ch18
5
3
1
-1
-3
-5
-7
-9
-11
-13
-15
-17
-19
-21
AT86RF231 TX Pout [dBm]
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7.2.3 TX Modulation Accuracy (EVM)
8340A-AVR-10/10
Figure 7-6. Error Vector Magnitude vs. TX Output Power.
EVM [%]
8
7,5
7
6,5
3.6 V
3.0 V
2.5 V
AVR2038
6
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
TX_PWR (Register Value)
Figure 7-7. Error Vector Magnitude vs. IEEE802.15.4 Channel (TX_PWR = 0).
EVM [%]
10
9
8
7
6
3.6 V
3.0 V
2.5 V
5
10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27
Channel
Ch19
13

7.2.4 RF Front-End Transmit Gain
7.2.5 Harmonics
14 AVR2038
Figure 7-8. RF Front-End Overall Transmit Gain.
RF Front-End Transmit Gain [dB]
23
22
21
20
19
18
17
16
15
14
13
12
11
10
9
8
7
6
3.6 V
3.3 V
3.0V
2.5 V
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
TX_PWR (Register Value)
Figure 7-9. TX P out and Harmonics vs. IEEE802.15.4 Channel (TX_PWR = 0)
Fundamental Output Power [dBm]
22
21
20
19
18
17
16
15
14
13
12
-60
10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27
Channel
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.
f0
2 f0
3 f0
4 f0
Ch18
-40
-42
-44
-46
-48
-50
-52
-54
-56
-58
Harmonic Output Power [dBm]
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7.2.6 Spurious Emissions – FCC
8340A-AVR-10/10
Figure 7-10. FCC Band Edge Spurious Emissions (conducted).
Power [dBm]
40
30
20
10
0
-10
-20
-30
-40
-50
-60
FCC part 15.247 limit
PSD
AVR2038
2200 2250 2300 2350 2400 2450 2500 2550 2600 2650 2700
Frequency [MHz]
RBW = 1 MHz, VBW = 10Hz
Figure 7-11. FCC Band Edge Spurious Emissions (conducted), Lower Band Edge.
Power [dBm]
40
30
20
10
0
-10
-20
-30
-40
-50
-60
PSD - Lower Channels
2385 2390 2395 2400 2405 2410 2415 2420
Frequency [MHz]
FCC part 15.247 limit
RBW = 1 MHz, VBW = 10Hz
15

16 AVR2038
Figure 7-12. FCC Band Edge Spurious Emissions (conducted), Upper Band Edge.
Power [dBm]
40
30
20
10
0
-10
-20
-30
-40
-50
-60
PSD - Higher Channels
2460 2465 2470 2475 2480 2485 2490 2495 2500
Frequency [MHz]
FCC part 15.247 limit
RBW = 1 MHz, VBW = 10Hz
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 2 nd
and 3 rd 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:
min{20 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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AVR2038
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 backoff
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.
Maximum TX Output Power [dBm]
23
22
21
20
19
18
17
3.6 V
40
16
3.0 V
2.7 V
30
15
3.6 V (DC)
20
14
3.0 V (DC)
2.7 V (DC)
10
13
0
10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27
Channel
100
90
80
70
60
50
Maximum Duty Cycle [%]
17

Appendix A – Design
A.1 - Schematic
18 AVR2038
Figure A.1-1. RCB231LPA – RF Front-End Section.
8340A-AVR-10/10

8340A-AVR-10/10
Figure A. 1-2. RCB231LPA – Transceiver Section.
AVR2038
19

20 AVR2038
8340A-AVR-10/10
Figure A. 1-3. RCB231LPA – MCU Section.
1
3
2
Q101
CSTCC3.68G-A
C101
100n
C102
100n
C103
100n
C104
10p
C105
10p
C106
22p
C107
22p
R101
10k
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
EXT0
SFM-115-L2-S-D-LC
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
EXT1
SFM-115-L2-S-D-LC
D1
rot
D2
rot
D3
rot
T1
Knitter TSS31N
R102 NC
R4
470
R5
470
R6
470
Batt1
AAAx2
C108
100n
L101
Wuerth74279266
VCC
VCC
VCC
R103 NC
R104 NC
SW1
Eao09.10201.02
(32kHz)
R105 0R
VCC
C109
10n
L102
Wuerth74279266
VCC
C110
100n
L103
Wuerth74279266
PG5(OC0B)
1
PE0(RXD0/PCINT8/PDI)
2
PE1(TXD0/PDO)
3
PE2(XCK0/AIN0)
4
PE3(OC3A/AIN1)
5
PE4(OC3B/INT4)
6
PE5(OC3C/INT5)
7
PE6(T3/INT6)
8
PE7(ICP3/CLKO/INT7)
9
PB0(/SS/PCINT0)
10
PB1(SCK/PCINT1)
11
PB2(MOSI/PCINT2)
12
PB3(MISO/PCINT3)
13
PB4(OC2A/PCINT4)
14
PB5(OC1A/PCINT5)
15
PB6(OC1B/PCINT6)
16
PB7(OC0A/OC1C/PCINT7)
17
PG3(TOSC2)
18
PG4(TOSC1)
19
RESET
20
Vcc
21
GND
22
XTAL2
23
XTAL1
24
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
Vcc
52
GND
53
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
AREF
62
AGND
63
AVcc
64
GND
65
U5
ATMEGA_1281
(RS-204-7871)
Q102
CFPX-157
AVcc
AREF
Plug1
AMP 2-331677-2
Plug2
AMP 2-331677-2
A
2
K
1
D4
BAS140W
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
AGND
#RESET
XTAL1
XTAL2
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
XTAL1
XTAL2
PD4
PD0
PD5
PD6
PD7
PD6
XTAL_1
XTAL_2
#RESET
#RESET
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
AGND
AVcc
RSTN
SLP_TR
CLKM
SCK
MISO
MOSI
SEL
IRQ
ICP1
Transceiver
Transceiver Section
VDD

A.2 – Assembly Drawing
8340A-AVR-10/10
Figure A. 2-4. RCB231LPA – Assembly Drawing.
AVR2038
21

A.3 – Bill of Material (BoM)
22 AVR2038
Quantity Comment Description Designator Footprint
1 WE_748421245 Balun Wuert 748421245 B1 BALUN0805
1 AAAx2 Battery Batt1 BH-421-3
1 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 0603
8 100n Capacitor C5, C6, C7, C101, C102,
C103, C108, C110
0402
4 10p Capacitor C9, C10, C104, C105 0402
2 1nF Capacitor C13, C16 0402
1 1p5 Capacitor C22 0402
1 0p5 Capacitor C28 0402
1 0p5 Capacitor C29 0402
1 10n Capacitor C109 0402
3 rot D1, D2, D3 LED0603
1 BAS140W Schottky Diode D4 SOD-323
1 SFM-115-L2-S-D-LC Connector 15x2-pol. EXT0 SFM15
1 SFM-115-L2-S-D-LC EXT1 SFM15
1 2450LP14B100S F1 0603-6
1 Si1563DH MOSFET IC1 SOT-SC70/6-Dual Co
1 39nH Inductor L1 0603
1 1,5nH Inductor L2 0402
1 4.7nH Inductor L3 0402
2 4.7nH Inductor L4, L5 0603
4 Wuerth74279266 L12, L101, L102, L103 0603
1 Logo 1 LG1 LOGO solder
1 Logo 2 LG2 LOGO solder
1 Nut NT1
1 M2,5x8 NT2
2 AMP 2-331677-2 Plug1, Plug2
1 16MHz / CL=10pF Crystal Siward A207-011 Q1 XTAL_4X2_5_small
1 CSTCC3.68G-A Q101 CSTCC
1 CFPX-157 Crystal Q102 CFPX
2 1M Resistor R1, R2 0402
3 n.b. Resistor R3, R8, R11 0402
4 470 Resistor R4, R5, R6, R7 0402
3 0R Resistor R9, R10, R105 0402
4 1k Resistor R12, R13, R14, R15 0402
1 100k Resistor R16 0402
2 10k Resistor R17, R101 0402
3 NC Resistor R102, R103, R104 0402
1 Shield_BMIS SH1 LT08AD4303F
1 Eao09.10201.02 Switch 1W SW1 EAO1XUM
1 Knitter TSS31N Pushbutton 1P T1 Taster_ITT
1 AT86RF231 802.15.4 2.4GHz TRX U1 MLF-32
1 NC7WV04 2x 2 Input Inverter U2 SC-70-6
1 AT25010A U3 Mini-Map-8
1 NC7WP32 2x 2 Input OR Gatter U4 SC-70-8
1 ATMEGA_1281 8-bit AVR uC U5 MLF64-M2
1 uPG2314T5N U6 TSON-6
2 AS222-92 U7, U8 SC-70/6
1 SMA 50Ohm X1 SMA_BU
8340A-AVR-10/10

Appendix B – Abbreviation
8340A-AVR-10/10
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
AVR2038
23

Appendix C – EVALUATION BOARD/KIT IMPORTANT NOTICE
24 AVR2038
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
8340A-AVR-10/10

References
8340A-AVR-10/10
AVR2038
[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.
25

Disclaimer
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8340A-AVR-10/10