AT86RF230_09 ATMEL [ATMEL Corporation], AT86RF230_09 Datasheet - Page 55

• Manufacturer Part Number: AT86RF230_09
• Description: Low Power 2.4 GHz Transceiver for ZigBee, IEEE 802.15.4, 6LoWPAN, RF4CE and ISM
• Manufacturer: ATMEL [ATMEL Corporation]

8.6.2 CCA Configuration and Request
8.6.3 Data Interpretation
8.6.4 Register Description
5131E-MCU Wireless-02/09
Bit
0x01
Read/Write
Reset value
Bit
0x01
Read/Write
Reset value
The CCA modes are configurable via register 0x08 (PHY_CC_CCA).
The 4 bit value 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].
Using the Basic Operating Mode, a CCA request can be initiated manually by setting
CCA_REQUEST = 1 in register 0x08 (PHY_CC_CCA), if the AT86RF230 is in any RX
state. The CCA computation is done over eight symbol periodes and the result is
accessible 140 µs after the request.
Note, it is not recommended to initiate manually a CCA measurement when using the
Extended Operating Mode.
The current channel status (CCA_STATUS) and the CCA completion status
(CCA_DONE) are accessible in register 0x01 (TRX_STATUS). Note, a read access to
this register clears register bits CCA_DONE and CCA_STATUS.
The completion of a measurement cycle is indicated by CCA_DONE = 1. If the radio
transceiver detected no signal (idle channel) during the measurement cycle, the
CCA_STATUS bit is set to 1.
When using the “energy above threshold” algorithm (mode 1 and mode 3) any received
power above CCA_ED_THRES level is interpreted as a busy channel. The “carrier
sense” algorithm (mode 2 and mode 3) reports a busy channel when detecting a
IEEE 802.15.4 signal above the RSSI_BASE_VAL (see parameter 11.7.16). The radio
transceiver is also able to detect signals below this value, but the detection probability
decreases with the signal power. It is almost zero at the radio transceivers sensitivity
level (see parameter 11.7.1).
Register 0x01 (TRX_STATUS)
The TRX_STATUS register signals the current state of the radio transceiver as well as
the status of the CCA measurement. Note, a read access to the register clears bits
CCA_DONE and CCA_STATUS.
• Bit 7 – CCA_DONE
This register indicates if a CCA request is completed. Each read access to register
0x01 resets the CCA_DONE bit.
CCA_DONE
R
R
7
0
3
0
CCA_STATUS
R
R
6
0
2
0
TRX_STATUS
Reserved
R
R
5
0
1
0
TRX_STATUS
AT86RF230
R
R
4
0
0
0
TRX_STATUS
TRX_STATUS
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