RF2968 datasheet(13/20 Pages) RFMD

13 / 20 page

Preliminary

11-129

RF2968

Rev A13 010912

In a read operation, the baseband sends the device address, READ bit (R/W = 1), and register address to the RF2968

followed by a “turn-around” bit which lasts half a clock cycle. This turn-around allows the RF2968 to drive its requested

data, via BDDATA, on the rising edges of BDCLK. Following the transfer of the last data bit (D[0]), the baseband drives

BnDEN high and resumes control of BDDATA on the falling edge of the first BDCLK pulse after BnDEN is driven high.

SeeFigure3.

The register address field allows up to 32 registers for various functions. The RF2968 implements only register

addresses 3-7 and 30-31.

Bit Number

Bit Name

Comments

7 - 15

N/A

Not Assigned

0 -6

RSSI[6:0]

The RSSI value indicates the average power measured during the first 10

µs

after a packet has been detected. The baseband reads this register to obtain

the current received signal strength indicator measurement. The RSSI value

may range from 0dBm to -127dBm in 1dB increments. (All 0’s indicates

0dBm; all 1’s indicates -127dBm.) The RSSI circuitry is designed to operate

from -20dBm to -80dBm with an accuracy of 4dB at -60dBm.

Example: RSSI[6:0]= [110101] indicates -53dBm.

BDCLK

BnDEN

Slave Driving BDDATA

Master Driving BDDATA

...

D15

BDDATA

don't

care

turn-around

R/W = read = 1

D14

Floating

Figure 3. DBus Read Programming Diagram

RF2968 Datasheet(PDF) 13 Page - RF Micro Devices