CC1150-RTY1 datasheet(24/67 Pages) TI

24 / 67 page

CC1150

SWRS037A

Page 24 of 60

13 Packet Handling Hardware Support

The

CC1150 has built-in hardware support for

packet oriented radio protocols.

In transmit mode, the packet handler can be

configured to add the following elements to the

packet stored in the TX FIFO:

•

A programmable number of preamble

bytes.

•

A two byte Synchronization Word. Can be

duplicated to give a 4-byte sync word

(recommended). It is not possible to only

insert preamble or only insert a sync word.

•

Optionally whitening the data with a PN9

sequence.

•

Optionally Interleave and Forward Error

Code the data.

•

Optionally compute and add a 2 byte CRC

checksum over the data field.

In a system where

CC1150 is used as the

transmitter and

CC1101 as the receiver the

recommended setting is 4-byte preamble and

4-byte sync word except for 500 kBaud data

rate where the recommended preamble length

is 8 bytes.

Note that register fields that control the packet

handling features should only be altered when

CC1150 is in the IDLE state.

13.1

Data whitening

From a radio perspective, the ideal over the air

data are random and DC free. This results in

the smoothest power distribution over the

occupied bandwidth. This also gives the

regulation loops in the receiver uniform

operation conditions (no data dependencies).

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 in the receiver.

With

CC1150, in combination with a CC1101 at

the

receiver

end,

this

can

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

12. The PN9 sequence is initialized to all 1’s.

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.

Setting

PKTCTRL0

.WHITE_DATA=1

recommended for all uses, except when over-

the-air compatibility with other systems is

needed.

Figure 12: Data Whitening in TX Mode

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