Rainbow-electronics ATmega128RFA1 Uživatelský manuál stáhnout pdf (Strana 108)

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101

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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

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

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

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

1 2 ... 103 104 105 106 107 108 109 110 111 112 113 ... 523 524

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