Features - NXP Semiconductors MC9S08SU16 Reference Manual

Introduction
The CRC module provides a programmable polynomial and other parameters required to
implement a 16-bit or 32-bit CRC standard.
The 16/32-bit code is calculated for 8 bits of data at a time.

16.2.1 Features

Features of the CRC module include:
• Hardware CRC generator circuit using a 16-bit or 32-bit programmable shift register
• Programmable initial seed value and polynomial
• Option to transpose input data or output data (the CRC result) bitwise or bytewise.
This option is required for certain CRC standards. A bytewise transpose operation is
not possible when accessing the CRC data register via 8-bit accesses. In this case, the
user's software must perform the bytewise transpose function.
• Option for inversion of final CRC result
• 8-bit CPU register programming interface
16.2.2 Block diagram
The following is a block diagram of the CRC.
TOT
DH1
DH0
Reverse
DL1 Logic
DL0
PH1
PH0
Combine
PL1
Logic
PL0
Figure 16-1. Programmable cyclic redundancy check (CRC) block diagram
16.2.3 Modes of operation
Various MCU modes affect the CRC module's functionality.
244
WAS
Seed
CRC Data
Checksum
CRC Engine
Data
Polynomial
MC9S08SU16 Reference Manual, Rev. 5, 4/2017
FXOR TOTR
NOT Reverse
Logic Logic
16-/32-bit Select
TCRC
NXP Semiconductors
DH1
DH0
DL1
DL0