CC1020RSSR Datasheet, PDF (72/92 Pages) Texas Instruments – Low-Power RF Transceiver for Narrowband Systems

CC1020
MODEM Register (0Dh)
REGISTER
NAME
MODEM[7]
MODEM[6:4]
-
ADC_DIV[2:0]
MODEM[3]
MODEM[2]
-
PN9_ENABLE
MODEM[1:0]
DATA_FORMAT[1:0]
Default
value
0
3
0
0
0
Active Description
-
Reserved, write 0
-
ADC clock divisor
0: Not supported
1: ADC frequency = XOSC frequency / 4
2: ADC frequency = XOSC frequency / 6
3: ADC frequency = XOSC frequency / 8
4: ADC frequency = XOSC frequency / 10
5: ADC frequency = XOSC frequency / 12
6: ADC frequency = XOSC frequency / 14
7: ADC frequency = XOSC frequency / 16
Note that the intermediate frequency should be as close
to 307.2 kHz as possible. ADC clock frequency is always
4 times the intermediate frequency and should therefore
be as close to 1.2288 MHz as possible.
-
Reserved, write 0
H Enable scrambling of TX and RX with PN9 pseudo-
random bit sequence
0: PN9 scrambling is disabled
1: PN9 scrambling is enabled (x⁹+x⁵+1)
The PN9 pseudo-random bit sequence can be used for
BER testing by only transmitting zeros, and then
counting the number of received ones.
-
Modem data format
0 (00): NRZ operation
1 (01): Manchester operation
2 (10): Transparent asynchronous UART operation, set
DCLK=0
3 (11): Transparent asynchronous UART operation, set
DCLK=1
DEVIATION Register (0Eh)
REGISTER
NAME
DEVIATION[7]
TX_SHAPING
DEVIATION[6 :4]
DEVIATION [3 :0]
TXDEV_X[2 :0]
TXDEV_M[3 :0]
Default
value
1
6
8
Active
H
-
-
Description
Enable Gaussian shaping of transmitted data
Recommended setting: TX_SHAPING=1
Transmit frequency deviation exponent
Transmit frequency deviation mantissa
Deviation in 402-470 MHz band:
FREF ·TXDEV_M ·2^{(TXDEV_X−16)}
Deviation in 804-960 MHz band:
FREF ·TXDEV_M ·2^{(TXDEV_X−15)}
On-off-keying (OOK) is used in RX/TX if TXDEV_M[3:0]=0
To find TXDEV_M given the deviation and TXDEV_X:
TXDEV_M = deviation·2^{(16−TXDEV_X)}/FREF
in 402-470 MHz band,
TXDEV_M = deviation·2^{(15−TXDEV_X)}/FREF
in 804-960 MHz band.
Decrease TXDEV_X and try again if TXDEV_M  8.
Increase TXDEV_X and try again if TXDEV_M  16.
SWRS046F
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