Rainbow Electronics ATmega128RFA1 - Manual (Page 108)

108
8266A-MCU Wireless-12/09
ATmega128RFA1
valid until the next TRX24_RX_END interrupt is issued, caused by a new frame
reception.
Table 9-39 RX_CRC_VALID Register Bits
Register Bits Value Description
0 CRC (FCS) not valid RX_CRC_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 µs.
• 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 2µs 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 9-40 RSSI Register Bits
Register Bits Value Description
0 Minimum RSSI value: P(RF) < -90 dBm
1 P(RF) = RSSI_BASE_VAL+3 · (RSSI-1)
[dBm]
2 ...
RSSI4:0
28 Maximum RSSI value: P(RF) ≥ -10 dBm
9.12.11 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 R R R
Initial Value 1 1 1 1
Bit 3 2 1 0
NA ($147) ED_LEVEL3 ED_LEVEL2 ED_LEVEL1 ED_LEVEL0 PHY_ED_LEVEL
Read/Write R R R R
Initial Value 1 1 1 1
This register contains the result of an Energy Detection measurement.
• Bit 7:0 – ED_LEVEL7:0 - Energy Detection Level
The minimum ED value (ED_LEVEL = 0) indicates a receiver power less than or equal
to RSSI_BASE_VAL. The range is 84 dB with a resolution of 1 dB and an absolute
accuracy of ±5 dB. A manual ED measurement can be initiated by a write access to this
register. A value of 0xFF signals that no measurement has yet been started (reset
value). The measurement duration is 8 symbol periods (128 µs) for a data rate of 250
kb/s. For High Data Rate Modes the automated measurement duration is reduced to 32