Datasheet

 2009 Microchip Technology Inc. DS39897C-page 265
PIC24FJ256GB110 FAMILY
21.3 Registers
There are four registers used to control programmable
CRC operation:
• CRCCON
• CRCXOR
• CRCDAT
• CRCWDAT
REGISTER 21-1: CRCCON: CRC CONTROL REGISTER
U-0 U-0 R/W-0 R-0 R-0 R-0 R-0 R-0
— — CSIDL VWORD4 VWORD3 VWORD2 VWORD1 VWORD0
bit 15 bit 8
R-0 R-1 U-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0
CRCFUL CRCMPT
— CRCGO PLEN3 PLEN2 PLEN1 PLEN0
bit 7 bit 0
Legend:
R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’
-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown
bit 15-14 Unimplemented: Read as ‘0’
bit 13 CSIDL: CRC Stop in Idle Mode bit
1 = Discontinue module operation when device enters Idle mode
0 = Continue module operation in Idle mode
bit 12-8 VWORD<4:0>: Pointer Value bits
Indicates the number of valid words in the FIFO. Has a maximum value of 8 when PLEN<3:0> > 7,
or 16 when PLEN<3:0>
7.
bit 7 CRCFUL: FIFO Full bit
1 = FIFO is full
0 = FIFO is not full
bit 6 CRCMPT: FIFO Empty Bit
1 = FIFO is empty
0 = FIFO is not empty
bit 5 Unimplemented: Read as ‘0’
bit 4 CRCGO: Start CRC bit
1 = Start CRC serial shifter
0 = CRC serial shifter turned off
bit 3-0 PLEN<3:0>: Polynomial Length bits
Denotes the length of the polynomial to be generated minus 1.