Si1000/1/2/3/4/5
SFR Definition 15.1. CRC0CN: CRC0 Control
Bit
Name
Type
Reset
R/W
0
R/W
0
R/W
0
7
6
5
4
3
2
1
0
CRC0SEL CRC0INIT CRC0VAL
R/W
0
R/W
0
R/W
0
CRC0PNT[1:0]
R/W
0
0
SFR Page = 0xF; SFR Address = 0x92
Bit
Name
7:5
4
Unused
CRC0SEL
Read = 000b; Write = Don’t Care.
CRC0 Polynomial Select Bit.
Function
This bit selects the CRC0 polynomial and result length (32-bit or 16-bit).
0: CRC0 uses the 32-bit polynomial 0x04C11DB7 for calculating the CRC result.
1: CRC0 uses the 16-bit polynomial 0x1021 for calculating the CRC result.
3
2
CRC0INIT
CRC0VAL
CRC0 Result Initialization Bit.
Writing a 1 to this bit initializes the entire CRC result based on CRC0VAL.
CRC0 Set Value Initialization Bit.
This bit selects the set value of the CRC result.
0: CRC result is set to 0x00000000 on write of 1 to CRC0INIT.
1: CRC result is set to 0xFFFFFFFF on write of 1 to CRC0INIT.
1:0 CRC0PNT[1:0]
CRC0 Result Pointer.
Specifies the byte of the CRC result to be read/written on the next access to
CRC0DAT. The value of these bits will auto-increment upon each read or write.
For CRC0SEL = 0:
00: CRC0DAT accesses bits 7–0 of the 32-bit CRC result.
01: CRC0DAT accesses bits 15–8 of the 32-bit CRC result.
10: CRC0DAT accesses bits 23–16 of the 32-bit CRC result.
11: CRC0DAT accesses bits 31–24 of the 32-bit CRC result.
For CRC0SEL = 1:
00: CRC0DAT accesses bits 7–0 of the 16-bit CRC result.
01: CRC0DAT accesses bits 15–8 of the 16-bit CRC result.
10: CRC0DAT accesses bits 7–0 of the 16-bit CRC result.
11: CRC0DAT accesses bits 15–8 of the 16-bit CRC result.
Note:
Upon initiation of an automatic CRC calculation, the third opcode byte fetched from program memory is
indeterminate. Therefore, writes to CRC0CN that initiate a CRC operation must be immediately followed by a
benign 3-byte instruction whose third byte is a don’t care. An example of such an instruction is a 3-byte MOV
that targets the CRC0FLIP register. When programming in ‘C’, the dummy value written to CRC0FLIP should
be a non-zero value to prevent the compiler from generating a 2-byte MOV instruction.
Rev. 1.0
161
SILABS [ SILICON LABORATORIES ]
