PIC24FJ256DA210 Datasheet, PDF (297/408 Pages) Microchip Technology – 64/100-Pin, 16-Bit Flash Microcontrollers with Graphics Controller and USB On-The-Go (OTG)

PIC24FJ256DA210 FAMILY
21.0 32-BIT PROGRAMMABLE
CYCLIC REDUNDANCY CHECK
(CRC) GENERATOR
Note:
This data sheet summarizes the features
of this group of PIC24F devices. It is not
intended to be a comprehensive reference
source. For more information, refer to the
“PIC24F Family Reference Manual”,
Section 41. “32-Bit Programmable
Cyclic Redundancy Check (CRC)”
(DS39729). The information in this data
sheet supersedes the information in the
FRM.
FIGURE 21-1:
CRC BLOCK DIAGRAM
CRCDATH
CRCDATL
The 32-bit programmable CRC generator provides a
hardware implemented method of quickly generating
checksums for various networking and security
applications. It offers the following features:
• User-programmable CRC polynomial equation,
up to 32 bits
• Programmable shift direction (little or big-endian)
• Independent data and polynomial lengths
• Configurable interrupt output
• Data FIFO
Figure 21-1 displays a simplified block diagram of the
CRC generator. A simple version of the CRC shift
engine is displayed in Figure 21-2.
Variable FIFO
(4x32, 8x16 or 16x8)
Shift Buffer
FIFO Empty
Event
LENDIAN
1
0
CRCWDATH
CRCWDATL
CRC Shift Engine
Shifter Clock
2 * FCY
CRCISEL
1 _CRC
0 Interrupt
Shift
Complete
Event
FIGURE 21-2:
CRC SHIFT ENGINE DETAIL
CRC Shift Engine
CRCWDATH
Shift Buffer
Data
X0
Bit 0
Read/Write Bus
X1
Bit 1
CRCWDATL
Xn⁽¹⁾
Bit n⁽¹⁾
Note 1: n = PLEN<4:1> + 1.
 2010 Microchip Technology Inc.
DS39969B-page 297