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)
8-bit
Microcontrollers
Application Note
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.
Rev. 8340A-AVR-10/10
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.
32 kHz 3.68 MHz
Expansion
Connector 1
ATmega1281
16 MHz
SPI / Ctrl
signals
RF Frontend
AT86RF231
Expansion
Connector 2
Pushbutton
LEDs
ID
EEPROM
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.
PB5 (RSTN)
PB0 (SEL)
RSTN
>1
PB1..3 (SPI)
SEL#
/RST
/SEL
Transceiver
AT86RF231
SPI
>1
#CS
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.
6
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
6.2.1
TOP
Operating temperature range
6.2.2
fRF
Operating frequency range
6.2.3
VCC
(1)
Min.
-20
2400
Supply voltage
2.7
Notes:
Typ.
(2)
3.0
Max.
Units
+70
°C
2483.5
MHz
3.6
V
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.
6.3.1
fRF
Frequency range
As specified in [3]
2405
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)
6.3.8
fXTAL_ACC XTAL frequency accuracy
6.3.9
tXTAL
XTAL settling time
6.3.10
B20dB
20dB bandwidth
(1)
330
2.8
Note:
Max.
Units
2480
MHz
16
-40
Leaving SLEEP state to clock
available at pin 17 (CLKM)
Typ.
MHz
+40
ppm
1000
µs
MHz
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.
6.4.1
PTX
TX Output power
Maximum configurable TX output
power value (2)
Register bit TX_PWR = 0
6.4.2
PRANGE
Output power range
16 steps, configurable in
register 0x05 (PHY_TX_PWR)
6.4.3
PACC
6.4.4
6.4.5
6.4.6
-4
(3)
PSPUR
+18
(1)
Max.
+21
(3)
15
Output power tolerance
8
Harmonics (FCC) (1)
2nd harmonic
rd
3 harmonic
Pout = Pmax
CW, no modulation
Spurious Emissions
30 – ≤1000MHz
>1 – 12.75GHz
1.8 – 1.9GHz
5.15 – 5.3GHz
Complies with
EN 300 328/440,
FCC-CFR-47 part 15,
ARIB STD-66, RSS-210
Notes:
Units
dBm
dB
±3
EVM
PHARM
Typ.
dB
% rms
-42
-50
dBm
dBm
-36
-30
-47
-47
dBm
dBm
dBm
dBm
(1)
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
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
Notes:
Min.
Typ.
Max.
0.02
Units
μA
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.
PA + PHY Current Consumption [mA]
140
120
100
80
60
40
3.6 V
3.3 V
3.0V
2.5 V
20
0
0
1
2
3
4
5
6
7
8
9
TX_PWR (Register Value)
Note:
10
10
11
12
13
14
15
Ch22
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.
PA + PHY Current Consumption [mA]
150
3.6 V
3.3 V
3.0 V
2.5 V
130
110
90
70
50
30
10
-6
-4
-2
0
2
4
6
8
10
12
14
16
18
20
TX output Power [dBm]
22
Ch22
Figure 7-3. Current Consumption vs. Channel (TX_PWR = 0).
PA + PHY Current Consumption [mA]
150
140
130
120
110
100
3.6 V
3.3 V
3.0 V
2.5 V
90
80
70
60
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
Channel
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7.2 TX Performance
7.2.1 TX Output Power
22
5
20
3
18
1
16
-1
14
-3
12
-5
10
-7
8
-9
6
-11
4
3.6 V
-13
2
3.3 V
-15
0
3.0V
-17
-2
2.5 V
-19
-4
AT86RF231
-21
-6
AT86RF231 TX Pout [dBm]
RCB231LPA TX Pout [dBm]
Figure 7-4. TX Output Power vs. TX_PWR.
-23
0
1
2
3
4
5
6
7
8
9
10
11
12
13
TX_PWR (Register Value)
14
15
Ch18
7.2.2 TX Output Power vs. IEEE802.15.4 Channel
Figure 7-5. TX Output Power vs. Channel (TX_PWR = 0).
22
21
TX Output Power [dBm]
20
19
18
17
16
15
3.6 V
3.3 V
3.0V
2.5 V
14
13
12
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
Channel
12
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7.2.3 TX Modulation Accuracy (EVM)
Figure 7-6. Error Vector Magnitude vs. TX Output Power.
8
EVM [%]
7,5
7
6,5
3.6 V
3.0 V
2.5 V
6
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
TX_PWR (Register Value)
15
Ch19
Figure 7-7. Error Vector Magnitude vs. IEEE802.15.4 Channel (TX_PWR = 0).
10
EVM [%]
9
8
7
3.6 V
6
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
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7.2.4 RF Front-End Transmit Gain
RF Front-End Transmit Gain [dB]
Figure 7-8. RF Front-End Overall Transmit Gain.
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
TX_PWR (Register Value)
14
15
Ch18
7.2.5 Harmonics
22
-40
21
-42
20
-44
19
-46
18
-48
17
-50
16
-52
15
-54
f0
2 f0
3 f0
4 f0
14
13
-56
Harmonic Output Power [dBm]
Fundamental Output Power [dBm]
Figure 7-9. TX Pout and Harmonics vs. IEEE802.15.4 Channel (TX_PWR = 0)
-58
12
-60
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
Channel
Note:
14
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
40
30
20
Power [dBm]
10
0
-10
-20
-30
FCC part 15.247 limit
-40
-50
-60
2200
2250
2300
2350
2400
2450
2500
Frequency [MHz]
2550
2600
2650
2700
RBW = 1 MHz, VBW = 10Hz
Figure 7-11. FCC Band Edge Spurious Emissions (conducted), Lower Band Edge.
PSD - Lower Channels
40
30
FCC part 15.247 limit
20
Power [dBm]
10
0
-10
-20
-30
-40
-50
-60
2385
2390
2395
2400
2405
Frequency [MHz]
2410
2415
2420
RBW = 1 MHz, VBW = 10Hz
15
8340A-AVR-10/10
Figure 7-12. FCC Band Edge Spurious Emissions (conducted), Upper Band Edge.
PSD - Higher Channels
40
30
20
Power [dBm]
10
0
-10
-20
-30
FCC part 15.247 limit
-40
-50
-60
2460
2465
2470
2475
2480
2485
2490
Frequency [MHz]
Note:
2495
2500
RBW = 1 MHz, VBW = 10Hz
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:
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.
16
AVR2038
8340A-AVR-10/10
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.
23
100
22
90
21
80
20
70
19
60
18
50
17
40
3.6 V
3.0 V
2.7 V
3.6 V (DC)
3.0 V (DC)
2.7 V (DC)
16
15
14
30
Maximum Duty Cycle [%]
Maximum TX Output Power [dBm]
Figure 7-13. AT86RF231 Range Extension Duty-Cycle and PA Back-Off.
20
10
13
0
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
Channel
17
8340A-AVR-10/10
Appendix A – Design
A.1 - Schematic
Figure A.1-1. RCB231LPA – RF Front-End Section.
18
AVR2038
8340A-AVR-10/10
AVR2038
Figure A. 1-2. RCB231LPA – Transceiver Section.
19
8340A-AVR-10/10
C110
100n
VCC
VCC
A K
C109
10n C106
22p
19
3
C104
10p
1
XTAL_2
XTAL_1
Q101
CSTCC3.68G-A
Eao09.10201.02
(RS-204-7871)
SW1
C102
100n
23
AAAx2
VCC
Plug2
AMP 2-331677-2
C107
22p
22
Batt1
CFPX-157
(32kHz)
Q102
2
Plug1
AMP 2-331677-2
BAS140W
2
18
1
#RESET
21
D4
10k
R101
24
Transceiver Section
XTAL_1
17
PD6
PG3(TOSC2)
NC
PB7(OC0A/OC1C/PCINT7)
R102
20
CLKM
PG4(TOSC1)
PD0
Vcc
NC
R104
VCC
C105
10p
NC
R103
25
PD4
RESET
26
0R
GND
27
R105
XTAL2
29
28
ICP1
XTAL1
PB5
PD0(SCL/INT0)
XTAL1
XTAL2
32
31
30
IRQ
PD1(SDA/INT1)
RSTN
PD4(ICP1)
PB4
PB3
AGND
PB2
PB6(OC1B/PCINT6)
PF1(ADC1)
MISO
16
PF2(ADC2)
MOSI
PB6
AREF
PB1
PB0
PB5(OC1A/PCINT5)
PB4(OC2A/PCINT4)
PF0(ADC0)
SCK
SEL
15
PB5
PB3(MISO/PCINT3)
PB2(MOSI/PCINT2)
PB1(SCK/PCINT1)
PD2(RXD1/INT2)
ATMEGA_1281
U5
VCC
PD3(TXD1/INT3)
PF7(ADC7/TDI)
SLP_TR
Transceiver
Wuerth74279266
14
PB4
12
PB2
13
11
PB1
PB0(/SS/PCINT0)
PF3(ADC3)
PB3
10
PB0
PE7(ICP3/CLKO/INT7)
PE6(T3/INT6)
PE5(OC3C/INT5)
PF5(ADC5/TMS)
L101
VDD
9
8
PE6
PE7
7
PE5
PE4(OC3B/INT4)
PE3(OC3A/AIN1)
PE2(XCK0/AIN0)
PF6(ADC6/TDO)
VCC
T1
6
PE1(TXD0/PDO)
PF4(ADC4/TCK)
Knitter TSS31N
5
PE4
GND
PE3
65
PE0(RXD0/PCINT8/PDI)
AVcc
4
64
PE2
63
AVcc
L103
Wuerth74279266
62
AGND
3
AREF
2
61
PE1
PE0
60
R4
470
59
PF1
PG5(OC0B)
PF2
R5
470
1
58
R6
470
D1
rot
57
AGND
D2
rot
PF0
56
AREF
D3
rot
PF3
C108
100n
AVcc
PF4
C101
100n
L102
Wuerth74279266
55
GND
PD0
VCC
54
PF6
Vcc
PD1
VCC
PF7
PD5(XCK1)
PB7
53
PA0(AD0)
#RESET
52
PD6(T1)
PD5
PF5
51
PD7(T0)
PA1(AD1)
PD2
PA0
PA2(AD2)
PD3
50
PD4
49
PA1
PD6
20
PA2
PD7
C103
100n
PG0(/WR)
PG1(/RD)
PC0(A8)
PC1(A9)
PC2(A10)
PC3(A11)
PC4(A12)
PC5(A13)
PC6(A14)
PC7(A15)
PG2(ALE)
PA7(AD7)
PA6(AD6)
PA5(AD5)
PA4(AD4)
PA3(AD3)
PA3
PA4
PA5
PA6
PA7
PG2
PC7
PC6
PC5
PC4
PC3
PC2
PC1
PC0
PG1
PG0
48
47
46
45
44
43
42
41
40
39
38
37
36
35
34
33
PC1
PC3
PC5
PC7
PG2
PD1
PD3
PD5
PD7
PG1
XTAL2
PB7
PA1
PA3
PA5
PA7
PE6
PE4
PE2
PE0
AREF
PF1
PF3
PF5
PF7
VCC
1
3
5
7
9
11
13
15
17
19
21
23
25
27
29
1
3
5
7
9
11
13
15
17
19
21
23
25
27
29
SFM-115-L2-S-D-LC
2
4
6
8
10
12
14
16
18
20
22
24
26
28
30
EXT0
SFM-115-L2-S-D-LC
2
4
6
8
10
12
14
16
18
20
22
24
26
28
30
EXT1
VCC
PC0
PC2
PC4
PC6
XTAL1
PD0
PD2
PD4
PD6
PG0
PB6
#RESET
PA0
PA2
PA4
PA6
PB1
PE7
PE5
PE3
PE1
AGND
PF0
PF2
PF4
PF6
Figure A. 1-3. RCB231LPA – MCU Section.
AVR2038
8340A-AVR-10/10
AVR2038
A.2 – Assembly Drawing
Figure A. 2-4. RCB231LPA – Assembly Drawing.
21
8340A-AVR-10/10
A.3 – Bill of Material (BoM)
Quantity
22
Comment
Description
Designator
Footprint
1
WE_748421245
Balun Wuert 748421245
B1
BALUN0805
1
1
AAAx2
47uF/6V
Battery
Electrolytic Capacitor
Batt1
C1
BH-421-3
TANTAL_C
14
22p
Capacitor
C3, C8, C15, C17, C19,
C20, C21, C23, C24, C25,
C26, C27, C106, C107
C4, C11, C12, C14
0402
4
1uF
Capacitor
8
100n
Capacitor
0603
4
10p
Capacitor
C5, C6, C7, C101, C102,
C103, C108, C110
C9, C10, C104, C105
0402
2
1nF
Capacitor
C13, C16
0402
1
1p5
Capacitor
C22
0402
0402
1
0p5
Capacitor
C28
0402
1
1
0p5
10n
Capacitor
Capacitor
C29
C109
0402
0402
D1, D2, D3
LED0603
Schottky Diode
D4
SOD-323
3
rot
1
BAS140W
1
SFM-115-L2-S-D-LC Connector 15x2-pol.
EXT0
SFM15
1
1
SFM-115-L2-S-D-LC
2450LP14B100S
EXT1
F1
SFM15
0603-6
1
Si1563DH
MOSFET
IC1
SOT-SC70/6-Dual Co
1
39nH
Inductor
L1
0603
1
1,5nH
Inductor
L2
0402
1
2
4
4.7nH
4.7nH
Wuerth74279266
Inductor
Inductor
L3
L4, L5
L12, L101, L102, L103
0402
0603
0603
1
Logo 1
LG1
LOGO solder
1
Logo 2
LG2
LOGO solder
1
Nut
NT1
1
2
M2,5x8
AMP 2-331677-2
NT2
Plug1, Plug2
1
16MHz / CL=10pF
1
CSTCC3.68G-A
Crystal Siward A207-011
Q1
XTAL_4X2_5_small
Q101
1
CFPX-157
Crystal
Q102
CSTCC
CFPX
2
3
1M
n.b.
Resistor
Resistor
R1, R2
R3, R8, R11
0402
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
2
100k
10k
Resistor
Resistor
R16
R17, R101
0402
0402
Resistor
R102, R103, R104
0402
SH1
LT08AD4303F
EAO1XUM
3
NC
1
Shield_BMIS
1
Eao09.10201.02
Switch 1W
SW1
1
Knitter TSS31N
Pushbutton 1P
T1
Taster_ITT
1
1
AT86RF231
NC7WV04
802.15.4 2.4GHz TRX
2x 2 Input Inverter
U1
U2
MLF-32
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
2
uPG2314T5N
AS222-92
U6
U7, U8
TSON-6
SC-70/6
1
SMA 50Ohm
X1
SMA_BU
AVR2038
8340A-AVR-10/10
AVR2038
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
23
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
24
AVR2038
8340A-AVR-10/10
AVR2038
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.
25
8340A-AVR-10/10
Disclaimer
Atmel Corporation
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San Jose, CA 95131
USA
Tel: (+1)(408) 441-0311
Fax: (+1)(408) 487-2600
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© 2010 Atmel Corporation. All rights reserved. / Rev.: CORP072610
®
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8340A-AVR-10/10