Cc2500-Compatible Pn9 Whitening; Pn7 Whitening - Texas Instruments CC253x User Manual

Bit-Stream Processor
The w register must be initialized by writing w into register BSP_W.W before starting receiving or
transmitting a packet. Doing this sets w
BSP_W[5]; w is set to 1.
0
When running normal receive or transmit tasks, writing to BSP_W is done by the LLE, which writes the
value in PRF_W_INIT to this register, but for test commands and co-processor mode, the BSP_W register
must be written by the MCU.
The PN7 whitener is enabled by the bit W_PN7_EN of the BSP_MODE register.
w
0
0
x
Output

25.4.2 CC2500-Compatible PN9 Whitening

The CC2500-compatible PN9 whitener is shown in
an 8-bit output register b. It produces a whitening sequence compatible with CC2500, CC2510 and other
TI devices. These devices use the polynomial x
at a time, and the byte is bit-reversed before being XORed with a received or transmitted byte. Before
starting reception or transmission of a packet, the s and b registers must be initialized to all ones by
writing a 1 to register BSP_W.W_PN9_RESET. As for the PN7 whitener, this is done by the LLE for normal
receive and transmit tasks, provided that bit 7 of PRF_W_INIT is 1.
In Figure 25-4, the dashed arrows going from the s blocks to the b blocks denote a copy that takes place
after the whitening of one byte is done. This means that the first byte is whitened by the 8 bits that are in
the b register after initialization (all ones). As this byte is being whitened, the s register is updated. After
the first byte is whitened, the value of the s register is copied into the b register and used for whitening the
second byte.
The CC2500-compatible whitener is enabled by bit W_PN9_EN of the BSP_MODE register.
292
CC2541 Proprietary Mode Radio
to BSP_W[0], w
6
w w w
1 2 3
Figure 25-3. PN7 Whitening
Figure
9 4
+ x
Copyright © 2009–2014, Texas Instruments Incorporated
to BSP_W[1] and so on up to w
5
w w
4 5
4
x
BSP_MODE.W_PN7_EN
25-4. It has a 9-bit whitening shift register s and
+ 1. The whitening sequence is produced one byte
SWRU191F – April 2009 – Revised April 2014
www.ti.com
to
1

PN7 Whitening

w
6
7
x
B0466-01
Submit Documentation Feedback