CC2500-RTR1 datasheet(26/84 Pages) TI

26 / 84 page

CC2500

PRELIMINARY Data Sheet (Rev.1.2)

SWRS040A

Page 26 of 83

15 Packet Handling Hardware Support

The

CC2500 has built-in hardware support for

packet oriented radio protocols.

In transmit mode, the packet handler will add

the following elements to the packet stored in

the TX FIFO:

•

A programmable number of preamble

bytes.

•

A two byte synchronization (sync) word.

Can be duplicated to give a 4-byte sync

word.

•

Optionally whiten the data with a PN9

sequence.

•

Optionally Interleave and Forward Error

Code the data.

•

Optionally compute and add a CRC

checksum over the data field.

•

The recommended setting is 4-byte

preamble and 4-byte sync word except for

500

kbps

data

rate

where

the

recommended preamble length is 8 bytes.

In receive mode, the packet handling support

will de-construct the data packet:

•

Preamble detection.

•

Sync word detection.

•

Optional one byte address check.

•

Optionally compute and check CRC.

•

Optionally append two status bytes (see

Table 21 and Table 22) with RSSI value,

Link Quality Indication and CRC status.

Bit

Field name

Description

7:0

RSSI

RSSI value

Table 21: Received packet status byte 1

(first byte appended after the data)

Bit

Field name

Description

CRC_OK

1: CRC for received data OK (or

CRC disabled)

0: CRC error in received data

6:0

LQI

The Link Quality Indicator

estimates how easily a received

signal can be demodulated

Table 22: Received packet status byte 2

(second byte appended after the data)

Note that register fields that control the packet

handling features should only be altered when

CC2500 is in the IDLE state.

15.1

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

CC2500, this can be done automatically

by 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.

Data whitening can only be used when

PKTCTRL0.CC2400_EN

= 0 (default).

CC2500-RTR1 数据表(PDF) 26 Page - Texas Instruments

CC2500-RTR1 数据表(HTML) 26 Page - Texas Instruments

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84

数据表下载