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Bit-Stream Processor
Table 25-9. Register Settings for Some Commonly Used CRCs, Assuming Initialization With All 1s
Order
CRC
PRF_CRC_LEN
BSP_Px
PRF_CRC_INIT
BSP_P0
= 0x00
PRF_CRC_INIT[0]
= 0x00
BSP_P1
= 0x00
PRF_CRC_INIT[1]
= 0x00
8
1
CRC-8-ATM x
8
+ x
2
+ x + 1
BSP_P2
= 0x00
PRF_CRC_INIT[2]
= 0x00
BSP_P3
= 0x07
PRF_CRC_INIT[3]
= 0xFF
BSP_P0
= 0x00
PRF_CRC_INIT[0]
= 0x00
BSP_P1
= 0x00
PRF_CRC_INIT[1]
= 0x00
8
1
CRC-8 x
8
+ x
7
+ x
6
+ x
4
+ x
2
+ 1
BSP_P2
= 0x00
PRF_CRC_INIT[2]
= 0x00
BSP_P3
= 0xD3
PRF_CRC_INIT[3]
= 0xFF
BSP_P0
= 0x00
PRF_CRC_INIT[0]
= 0x00
CRC-16 (used in CC2500) x
16
+ x
15
+
BSP_P1
= 0x00
PRF_CRC_INIT[1]
= 0x00
16
2
x
2
+ 1
BSP_P2
= 0x05
PRF_CRC_INIT[2]
= 0xFF
BSP_P3
= 0x80
PRF_CRC_INIT[3]
= 0xFF
BSP_P0
= 0x00
PRF_CRC_INIT[0]
= 0x00
BSP_P1
= 0x00
PRF_CRC_INIT[1]
= 0x00
16
2
CRC-16-CCITT x
16
+ x
12
+ x
5
+ 1
BSP_P2
= 0x21
PRF_CRC_INIT[2]
= 0xFF
BSP_P3
= 0x10
PRF_CRC_INIT[3]
= 0xFF
BSP_P0
= 0x00
PRF_CRC_INIT[0]
= 0x00
CRC-24 x
24
+ x
22
+ x
20
+ x
19
+ x
18
+ x
16
BSP_P1
= 0xCB
PRF_CRC_INIT[1]
= 0xFF
24
3
+ x
14
+ x
13
+ x
11
+ x
10
+ x
8
+ x
7
+ x
6
+ x
3
BSP_P2
= 0x6D
PRF_CRC_INIT[2]
= 0xFF
+ x + 1
BSP_P3
= 0x5D
PRF_CRC_INIT[3]
= 0xFF
BSP_P0
= 0xB7
PRF_CRC_INIT[0]
= 0xFF
CRC-32-IEEE 802.3 x
32
+ x
26
+ x
23
+
BSP_P1
= 0x1D
PRF_CRC_INIT[1]
= 0xFF
32
4
x
22
+ x
16
+ x
12
+ x
11
+ x
10
+ x
8
+ x
7
+ x
5
BSP_P2
= 0xC1
PRF_CRC_INIT[2]
= 0xFF
+ x
4
+ x
2
+ x + 1
BSP_P3
= 0x04
PRF_CRC_INIT[3]
= 0xFF
25.4.4 Coprocessor Mode
The coprocessor mode is used to run the BSP as a stand-alone and not part of the signal path. It must not
be used while the LLE is running. Coprocessor mode is selected by setting
BSP_MODE.CP_MODE
to 01 or
11. In these modes, one byte to be processed is written to the
BSP_DATA
register, and the result of
processing this byte can later be read back from the same register. When
BSP_MODE.CP_MODE
is 01, the
coprocessor is in receive mode, where the whitener is applied before the CRC. When
BSP_MODE.CP_MODE
is 11, the coprocessor is in transmit mode, where the whitener is applied after the
CRC.
To apply the BSP operations to a byte, write it to the
BSP_DATA
register. When this register is written to,
the
BSP_MODE.CP_BUSY
bit goes high.
If
CP_MODE.CP_END
is 0, the first bit provided is the LSB and the last bit is the MSB. If
CP_MODE.CP_END
is 1, the first bit provided is the MSB and the last bit is the LSB.
When
BSP_MODE.CP_BUSY
goes low, the processed data can be read from the
BSP_DATA
register. If one
or both whiteners are enabled, this byte is whitened or de-whitened. Otherwise, it is the same as the byte
written, except if the CRC is being read as described in the following text.
To read out a CRC in transmit mode, set
BSP_MODE.CP_READOUT
to 1. A zero must be written to the
BSP_DATA
register, and when
BSP_MODE.CP_BUSY
goes low, a CRC byte can be read from
BSP_DATA
.
This should be repeated for each CRC byte. If whitening is enabled, the read back CRC bytes are
whitened.
The BSP must not be set in coprocessor mode while the LLE is processing a packet.
308
CC2541 Proprietary Mode Radio
SWRU191C
–
April 2009
–
Revised January 2012
Copyright
©
2009
–
2012, Texas Instruments Incorporated