ATmega1284PR231 Atmel Corporation, ATmega1284PR231 Datasheet - Page 91

• Manufacturer Part Number: ATmega1284PR231
• Manufacturer: Atmel Corporation

Specifications of ATmega1284PR231

• Flash (kbytes): 128 Kbytes
• Max. Operating Frequency: 20 MHz
• Max I/o Pins: 32
• Spi: 3
• Twi (i2c): 1
• Uart: 2
• Adc Channels: 8
• Adc Resolution (bits): 10
• Adc Speed (ksps): 15
• Analog Comparators: 1
• Crypto Engine: AES
• Sram (kbytes): 16
• Eeprom (bytes): 4096
• Operating Voltage (vcc): 1.8 to 3.6
• Timers: 3
• Frequency Band: 2.4 GHz
• Max Data Rate (mb/s): 2
• Antenna Diversity: Yes
• External Pa Control: Yes
• Power Output (dbm): 3
• Receiver Sensitivity (dbm): -101
• Receive Current Consumption (ma): 13.2
• Transmit Current Consumption (ma): 14.4
• Link Budget (dbm): 104

8.4
8.4.1
8.4.2
8111C–MCU Wireless–09/09
Energy Detection (ED)
Overview
Measurement Description
The Energy Detection (ED) module is characterized by:
The receiver ED measurement is used by the network layer as part of a channel selection algo-
rithm. It is an estimation of the received signal power within the bandwidth of an IEEE 802.15.4
channel. No attempt is made to identify or decode signals on the channel. The ED value is cal-
culated by averaging RSSI values over eight symbols (128 µs).
For High Data Rate Modes the automated ED measurement duration is reduced to 32 µs, refer
to
in these modes the measurement period is still 128 µs as long as the receiver is in RX_ON state.
There are two ways to initiate an ED measurement:
For manually initiated ED measurements the radio transceiver needs to be in one of the states
RX_ON or BUSY_RX state. The end of the ED measurement is indicated by an interrupt
IRQ_4 (CCA_ED_DONE).
An automated ED measurement is started if an SHR is detected. The end of the automated
measurement is not signaled by an interrupt.
The measurement result is stored after t
cessing delay) in register 0x07 (PHY_ED_LEVEL).
Thus by using Basic Operating Mode, a valid ED value from the currently received frame is
accessible 108 µs after IRQ_2 (RX_START) and remains valid until a new RX_START interrupt
is generated by the next incoming frame or until another ED measurement is initiated.
By using the Extended Operating Mode, it is recommended to mask IRQ_2 (RX_START), thus
the interrupt cannot be used as timing reference. A successful frame reception is signalized by
interrupt IRQ_3 (TRX_END). The minimum time span between a TRX_END interrupt and a fol-
lowing SFD detection is t
measurement time, the ED value needs to be read within 224 µs after the TRX_END interrupt;
otherwise, it could be overwritten by the result of the next measurement cycle. This is important
for time critical applications or if interrupt IRQ_2 (RX_START) is not used to indicate the recep-
tion of a frame.
Note, it is not recommended to manually initiate an ED measurement when using the Extended
Operating Mode.
The values of the register 0x07 (PHY_ED_LEVEL) are:
Table 8-7.
• 85 unique energy levels defined
• 1 dB resolution
• Manually, by writing an arbitrary value to register 0x07 (PHY_ED_LEVEL), or
• Automatically, after detection of a valid SHR of an incoming frame.
Section 11.3 “High Data Rate Modes” on page
PHY_ED_LEVEL
0x00.... 0x54
0xFF
Register Bit PHY_ED_LEVEL Interpretation
Description
Reset value
ED measurement result of the last ED measurement
TR27
= 96 µs due to the length of the SHR. Including the ED
TR26
= 140 µs (128 µs measurement duration and pro-
137. For manually initiated ED measurements
AT86RF231
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