CC2550-RTY1 datasheet(19/55 Pages) TI

19 / 55 page

CC2550

PRELIMINARY Data Sheet (Rev.1.2)

SWRS039A

Page 19 of 54

Figure 9: Data whitening in TX mode

13.2

Packet format

The format of the data packet can be

configured and consists of the following items

(see Figure 10):

•

Preamble

•

Synchronization word

•

Length byte or constant programmable

packet length

•

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 10: Packet format

The preamble pattern is an alternating

sequence of ones and zeros (01010101…).

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

preamble bytes until the first byte is written to

the TX FIFO. The modulator will then send the

sync word and then the data bytes. The

number of preamble bytes is programmed with

the MDMCFG1.NUM_PREAMBLE value.

The synchronization word is a two-byte value

set in the SYNC1 and SYNC0 registers. The

sync word provides byte synchronization of the

incoming packet. A one-byte synch word can

be emulated by setting the SYNC1 value to the

preamble pattern. It is also possible to emulate

bit

sync

word

using

MDMCFG2.SYNC_MODE=

3 or 7. The sync word

will then be repeated twice.

CC2550-RTY1 数据表(PDF) 19 Page - Texas Instruments

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