Datasheet

© 2009-2012 Microchip Technology Inc. Preliminary DS70616F-page 459
dsPIC33EPXXX(GP/MC/MU)806/810/814 and PIC24EPXXX(GP/GU)810/814
27.3 Programmable CRC Registers
REGISTER 27-1: CRCCON1: CRC CONTROL REGISTER 1
R/W-0 U-0 R/W-0 R-0 R-0 R-0 R-0 R-0
CRCEN — CSIDL VWORD<4:0>
bit 15 bit 8
R-0 R-1 R/W-0 R/W-0 R/W-0 U-0 U-0 U-0
CRCFUL CRCMPT CRCISEL CRCGO LENDIAN
— — —
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 CRCEN: CRC Enable bit
1 = CRC module is enabled
0 = CRC module is disabled. All state machines, pointers, and CRCWDAT/CRCDAT are reset. Other
SFRs are not reset.
bit 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<4:0> > 7,
or 16 when PLEN<4:0> ≤ 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 CRCISEL: CRC Interrupt Selection bit
1 = Interrupt on FIFO empty; final word of data is still shifting through CRC
0 = Interrupt on shift complete and CRCWDAT results ready
bit 4 CRCGO: Start CRC bit
1 = Start CRC serial shifter
0 = CRC serial shifter is turned off
bit 3 LENDIAN: Data Word Little-Endian Configuration bit
1 = Data word is shifted into the CRC starting with the LSb (little endian)
0 = Data word is shifted into the CRC starting with the MSb (big endian)
bit 2-0 Unimplemented: Read as ‘0’