SLAAEU2 August   2025 MSPM0C1104

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Introduction
    1. 1.1 System Introduction
    2. 1.2 MSPM0C110x Introduction
    3. 1.3 MCF8315D Introduction
  5. 2Hardware Setup
    1. 2.1 LP-MSPM0C1104 Hardware Setup
    2. 2.2 MCF8315PWPEVM Hardware Setup
  6. 3Software Structure
    1. 3.1 Software Function and Flow Diagram
    2. 3.2 Project File Structure
    3. 3.3 Configure and Control MCF8315
      1. 3.3.1 MCF8315D I2C Protocol Description
      2. 3.3.2 CRC Verification and Parity Check
      3. 3.3.3 MCF EEPROM or RAM Program
  7. 4System Test
    1. 4.1 Test Setup
    2. 4.2 System Value Monitor
  8. 5Summary
  9. 6References

3.3.2 CRC Verification and Parity Check

An 8-bit CCIT polynomial (x8 + x2+ x + 1) and CRC initial value 0xFF is used for CRC computation.

CRC Calculation in Write Operation: MCF8315D checks whether the MCU CRC byte is aligned with the CCIT polynomial when the external MCU writes to MCF8315D and the CRC is enabled. If there is a mismatch, then the write request is discarded. Input data for CRC calculation by external MCUs for write operations are listed below:

  • Target ID + write bit
  • Control word – 3 bytes
  • Data bytes – 2/4/8 bytes

CRC Calculation in Read Operation: When the external MCU reads from MCF8315D, if the CRC is enabled, MCF8315D sends the CRC byte at the end of the data. Input data for CRC calculation by external MCU to verify the data sent by MCF8315D are listed below:

  • Target ID + write bit
  • Control word – 3 bytes
  • Target ID + read bit
  • Data bytes – 2/4/8 bytes

Parity Calculation in Read/Write Operation: MCF8315D calculates the parity internally following the rules below once the EEPROM is programed and write data to EEPROM parity bit is ignored.

  • If the sum of the bits is even, then parity is 0.
  • If the sum of the bits is odd, then add 1 to parity to make be even.