Preliminary Technical Data

ADF7021

Rev. PrI | Page 35 of 44

REGISTER 7—READBACK SETUP REGISTER

AD1

AD2

RB1

RB2

RB3

DB8

DB7

DB6

DB5

DB4

DB3

DB2

C2 (1) C1 (1)

CONTROL

BITS

DB1

DB0

C3 (1)

C4 (0)

READBACK

SELECT

ADC

MODE

AD2

0

0

1

1

AD1

0

1

0

1

ADC MODE

MEASURE RSSI

BATTERY VOLTAGE

TEMP SENSOR

TO EXTERNAL PIN

RB2

0

0

1

1

RB1

0

1

0

1

READBACK MODE

AFC WORD

ADC OUTPUT

FILTER CAL

SILICON REV

RB3

0

1

READBACK

DISABLED

ENABLED

Figure 39.

Register 7—Readback Setup Register Comments

•

Readback of the measured RSSI value is valid only in Rx mode. To enable readback of the battery voltage, the temperature sensor, or

the voltage at the external pin in Rx mode, users need to disable AGC function in Register 9. To read back these parameters in Tx

mode, first power up the ADC using Register 8, as this is off by default in Tx mode to save power. This is the recommended method

of using the battery readback function, as most configurations typically require AGC.

•

AFC readback:

•

•

•

See the Readback Format section for more information.