ATmega1284PR231 Atmel Corporation, ATmega1284PR231 Datasheet - Page 94

• 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

8.5
8.5.1
8.5.2
8111C–MCU Wireless–09/09
Clear Channel Assessment (CCA)
Overview
Configuration and Request
The main features of the Clear Channel Assessment (CCA) module are:
A CCA measurement is used to detect a clear channel. Four modes are specified by
IEEE 802.15.4 - 2006:
Table 8-8.
The CCA modes are configurable via register 0x08 (PHY_CC_CCA).
Using the Basic Operating Mode, a CCA request can be initiated manually by setting
CCA_REQUEST = 1 (register 0x08, PHY_CC_CCA), if the AT86RF231 is in any RX state. The
current channel status (CCA_STATUS) and the CCA completion status (CCA_DONE) are
accessible in register 0x01 (TRX_STATUS).
The CCA evaluation is done over eight symbol periods and the result is accessible
t
of a manually initiated CCA measurement is indicated by an interrupt IRQ_4 (CCA_ED_DONE).
The sub-register CCA_ED_THRES of register 0x09 (CCA_THRES) defines the received power
threshold of the "Energy above threshold" algorithm. The threshold is calculated by
RSSI_BASE_VAL + 2 * CCA_ED_THRES [dBm]. Any received power above this level is inter-
preted as a busy channel.
Note, it is not recommended to manually initiate a CCA measurement when using the Extended
Operating Mode.
TR28
CCA Mode
• All 4 modes are available as defined by IEEE 802.15.4-2006 in section 6.9.9
• Adjustable threshold for energy detection algorithm
0, 3
= 140 µs (128 µs measurement duration and processing delay) after the request. The end
1
2
CCA Mode Overview
Description
Energy above threshold.
CCA shall report a busy medium upon detecting any energy above the ED threshold.
Carrier sense only.
CCA shall report a busy medium only upon the detection of a signal with the modulation
and spreading characteristics of an IEEE 802.15.4 compliant signal. The signal strength
may be above or below the ED threshold.
Carrier sense with energy above threshold.
CCA shall report a busy medium using a logical combination of
Where the logical operator may be configured as either OR (mode 0) or AND (mode 3).
– Detection of a signal with the modulation and spreading
– Energy above the ED threshold.
characteristics of this standard and
AT86RF231
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