CC1100-RTR1 datasheet(32/100 Pages) TI1

32 / 100 page

CC1100

SWRS038D

Page 32 of 92

Real world data often contain long sequences

of zeros and ones. Performance can then be

improved by whitening the data before

transmitting, and de-whitening the data in the

receiver. With

CC1100, this can be done

automatically

setting

PKTCTRL0.WHITE_DATA=1

. All data, except

the preamble and the sync word, are then

XOR-ed with a 9-bit pseudo-random (PN9)

sequence before being transmitted, as shown

in Figure 10. At the receiver end, the data are

XOR-ed

with

the

same

pseudo-random

sequence. This way, the whitening is reversed,

and the original data appear in the receiver.

The PN9 sequence is initialized to all 1’s.

Figure 10: Data Whitening in TX Mode

15.2 Packet Format

The format of the data packet can be

configured and consists of the following items

(see Figure 11):

•

Preamble

•

Synchronization word

•

Optional length byte

•

Optional address byte

•

Payload

•

Optional 2 byte CRC

•

Preamble bits

(1010...1010)

Data field

Optional CRC-16 calculation

Optionally FEC encoded/decoded

8 x n bits

16/32 bits

bits

8 x n bits

16 bits

Optional data whitening

Legend:

Inserted automatically in TX,

processed and removed in RX.

Optional user-provided fields processed in TX,

processed but not removed in RX.

Unprocessed user data (apart from FEC

and/or whitening)

Figure 11: Packet Format

The preamble pattern is an alternating

sequence of ones and zeros (10101010…).

The minimum length of the preamble is

programmable.

When

enabling

TX,

the

modulator will start transmitting the preamble.

When the programmed number of preamble

bytes has been transmitted, the modulator will

send the sync word and then data from the TX

FIFO if data is available. If the TX FIFO is

empty, the modulator will continue to send

CC1100-RTR1 Datasheet(PDF) 32 Page - Texas Instruments

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