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42073A-MCU Wireless-02/13
ATmega2564/1284/644RFR2
The PHY_RSSI register is a multi purpose register that indicates FCS validity, provides
random numbers and shows the current RSSI value.
Bit 7 – RX_CRC_VALID - Received Frame CRC Status
Reading this register bit indicates whether the last received frame has a valid FCS or
not. The register bit is updated when issuing a TRX24_RX_END interrupt and remains
valid until the next TRX24_RX_END interrupt is issued, caused by a new frame
reception.
Table 9-43 RX_CRC_VALID Register Bits
Register Bits
Value
Description
RX_CRC_VALID
0
CRC (FCS) not valid
1
CRC (FCS) valid
Bit 6:5 – RND_VALUE1:0 - Random Value
A 2-bit random value can be retrieved by reading register bits RND_VALUE. The value
can be used for random numbers for security applications. Note that the radio
transceiver shall be in Basic Operating Mode receive state. The values are updated
every 1 s. Ensure that register bit RX_PDT_DIS (register RX_SYN) is set to 0 at least
1 s before reading a random value.
Bit 4:0 – RSSI4:0 - Receiver Signal Strength Indicator
The result of the automated RSSI measurement is stored in these register bits. The
value is updated every 2s in receive states. The read value is a number between 0
and 28 indicating the received signal strength as a linear curve on a logarithmic input
power scale (dBm) with a resolution of 3 dB. A RSSI value of 0 indicates a RF input
power lower than RSSI_BASE_VAL (-90 dBm). A value of 28 marks a power higher or
equal to -10 dBm.
Table 9-44 RSSI Register Bits
Register Bits
Value
Description
RSSI4:0
0
Minimum RSSI value: P(RF) < -90 dBm
1
P(RF) = RSSI_BASE_VAL+3 (RSSI-1)
[dBm]
2
...
28
Maximum RSSI value: P(RF) ≥ -10 dBm
9.12.12 PHY_ED_LEVEL – Transceiver Energy Detection Level Register
Bit
7
6
5
4
NA ($147)
ED_LEVEL7
ED_LEVEL6
ED_LEVEL5
ED_LEVEL4
PHY_ED_LEVEL
Read/Write
R
Initial Value
1
Bit
3
2
1
0
NA ($147)
ED_LEVEL3
ED_LEVEL2
ED_LEVEL1
ED_LEVEL0
PHY_ED_LEVEL
Read/Write
R
Initial Value
1
This register contains the result of an Energy Detection measurement.
Bit 7:0 – ED_LEVEL7:0 - Energy Detection Level