Datasheet

PIC32MX1XX/2XX
DS61168E-page 106 Preliminary  2011-2012 Microchip Technology Inc.
REGISTER 9-4: DCRCCON: DMA CRC CONTROL REGISTER
Bit
Range
Bit
31/23/15/7
Bit
30/22/14/6
Bit
29/21/13/5
Bit
28/20/12/4
Bit
27/19/11/3
Bit
26/18/10/2
Bit
25/17/9/1
Bit
24/16/8/0
31:24
U-0 U-0 R/W-0 R/W-0 R/W-0 U-0 U-0 R/W-0
— —BYTO<1:0>WBO
(1)
— —BITO
23:16
U-0 U-0 U-0 U-0 U-0 U-0 U-0 U-0
— — — — — — — —
15:8
U-0 U-0 U-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0
— — — PLEN<4:0>
7:0
R/W-0 R/W-0 R/W-0 U-0 U-0 R/W-0 R/W-0 R/W-0
CRCEN CRCAPP
(1)
CRCTYP — — CRCCH<2:0>
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 31-30 Unimplemented: Read as ‘0’
bit 29-28 BYTO<1:0>: CRC Byte Order Selection bits
11 = Endian byte swap on half-word boundaries (i.e., source half-word order with reverse source byte order
per half-word)
10 = Swap half-words on word boundaries (i.e., reverse source half-word order with source byte order per
half-word)
01 = Endian byte swap on word boundaries (i.e., reverse source byte order)
00 = No swapping (i.e., source byte order)
bit 27 WBO: CRC Write Byte Order Selection bit
(1)
1 = Source data is written to the destination re-ordered as defined by BYTO<1:0>
0 = Source data is written to the destination unaltered
bit 26-25 Unimplemented: Read as ‘0’
bit 24 BITO: CRC Bit Order Selection bit
When CRCTYP (DCRCCON<15>) =
1 (CRC module is in IP Header mode):
1 = The IP header checksum is calculated Least Significant bit (LSb) first (i.e., reflected)
0 = The IP header checksum is calculated Most Significant bit (MSb) first (i.e., not reflected)
When CRCTYP (DCRCCON<15>) =
0 (CRC module is in LFSR mode):
1 = The LFSR CRC is calculated Least Significant bit first (i.e., reflected)
0 = The LFSR CRC is calculated Most Significant bit first (i.e., not reflected)
bit 23-13 Unimplemented: Read as ‘0’
bit 12-8 PLEN<4:0>: Polynomial Length bits
When CRCTYP (DCRCCON<15>) =
1 (CRC module is in IP Header mode):
These bits are unused.
When CRCTYP (DCRCCON<15>) =
0 (CRC module is in LFSR mode):
Denotes the length of the polynomial – 1.
bit 7 CRCEN: CRC Enable bit
1 = CRC module is enabled and channel transfers are routed through the CRC module
0 = CRC module is disabled and channel transfers proceed normally
Note 1: When WBO = 1, unaligned transfers are not supported and the CRCAPP bit cannot be set.