C8051F91X-C8051F90X 查看數據表（PDF） - Silicon Laboratories

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C8051F91X-C8051F90X

Single/Dual Battery, 0.9–3.6 V, 16–8 kB, SmaRTClock, 12/10-Bit ADC MCU

Silicon Laboratories 

C8051F91x-C8051F90x

SFR Definition 15.1. CRC0CN: CRC0 Control

Bit

7

6

5

4

3

2

1

0

Name

CRC0SEL CRC0INIT CRC0VAL CRC0PNT[1:0]

Type R/W

R/W

R/W

R/W

R/W

R/W

R/W

Reset

0

0

0

0

0

0

0

0

SFR Page = 0xF; SFR Address = 0x92

Bit

Name

Function

7:5 Unused Unused.

Read = 000b; Write = Don’t Care.

4 CRC0SEL CRC0 Polynomial Select Bit.

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 CRC0INIT CRC0 Result Initialization Bit.

Writing a 1 to this bit initializes the entire CRC result based on CRC0VAL.

2 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

155

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