Preamble bits
(1010...1010)
S
y
n
c w
o
rd
L
e
n
g
th f
ie
ld
A
d
d
re
s
s f
ie
ld
Data field
C
R
C
-1
6
Optional CRC-16 calculation
Optionally FEC encoded/decoded
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)
8 x n bits
16/32
bits
8
bits
8
bits
8 x n bits
16 bits
TX_OUT[7:0]
TX_DATA
8
7
6
5
4
3
2
1
0
7
6
5
4
3
2
1
0
The first TX_DATA byte is shifted in before doing the XOR-operation providing the first TX_OUT[7:0] byte. The
second TX_DATA byte is then shifted in before doing the XOR-operation providing the second TX_OUT[7:0] byte.
SWRS037B – JANUARY 2006 – REVISED MARCH 2015
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 be done automatically by setting PKTCTRL0WHITE_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
. The PN9 sequence is initialized to all ones. 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 is recommended for all uses, except when over-the-air compatibility
with other systems is needed.
Figure 5-7. Data Whitening in TX Mode
5.8.2
Packet Format
The format of the data packet can be configured and consists of the following items:
•
Preamble
•
Synchronization word
•
Optional length byte
•
Optional Address byte
•
Payload
•
Optional 2 byte CRC
Figure 5-8. Packet Format
20
Detailed Description
Copyright © 2006–2015, Texas Instruments Incorporated
Product Folder Links:
Содержание CC1150
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