Microchip Technology AC164139 Data Sheet

 2010 Microchip Technology Inc.

DS39969B-page 297

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.

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.

CRC

Interrupt

Variable FIFO

(4x32, 8x16 or 16x8)

Shift Buffer

CRC Shift Engine

Shifter Clock

2 * F

CY

1

0

CRCISEL

1

0

FIFO Empty

Event

Shift 

Complete

Event

Note 1: n = PLEN<4:1> + 1.

CRC Shift Engine

Bit 0

Bit 1

Bit n

X0

X1

Xn

Read/Write Bus

Shift Buffer

Data