If you read out the current registers you can generate other examples and test patterns.
I could build a table driven variant, fund work via https://paypal.me/cliveone
// CRC5 0x05/0x25 Polynomial Example - sourcer32@gmail.com
// Copyright (C) 2022, C Turvey, All Rights Reserved
// ST PMIC CRC Generation Test, L9369 via L5965 docs
#include <windows.h>
#include <stdio.h>
#include <stdlib.h>
typedef unsigned char uint8_t;
typedef unsigned short uint16_t;
typedef unsigned long uint32_t;
/*
https://www.st.com/resource/en/datasheet/l5965.pdf
SPI frame CRC generator
The SPI protocol is defined by frames of 32 bits with 5 bits of CRC (Cyclic
Redundancy Check) in both input and output directions. The polynomial
calculation implemented is: g(x)= x^5 + x^2 + 1 the structure of CRC generator
is shown in Figure 25. Structure of CRC generator.
Here are the rules:
1. For DI, CNT=DI[21] is ignored when calculating CRC, it means
only {DI[31:22],DI[20:5]} is used to calculate CRC. For example,
if DI[31:5]=27'b1000_0010_1011_1111_1111_1111_111, the CRC[4:0]= 5'b0_0011
2. For DO, DO[21] is ignored when calculating CRC, it means only
{DO[31:22],DO[20:5]} is used to calculate CRC.
3. The initial value of CRC generator is 5'b1_1111.
4. MSB (DI[31]) is shift in CRC generator at first.
*/
int main(int argc, char **argv) // Copyright (C) 2022 sourcer32@gmail.com
{
int i;
uint32_t test = 0x82BFFFE0; // 0x03
uint32_t crc;
crc = 0x1F << 27; // Initial, aligned high-order to match data
crc = crc ^ test; // Apply data
for(i=0; i<27; i++) // Consume data
if (crc & 0x80000000)
crc = (crc << 1) ^ (0x05 << 27); // Bitwise application
else
crc <<= 1;
crc = (crc >> 27) & 0x1F; // Recover, align, mask computed value
printf("CRC:%02X (03?) -> %08X\n", crc, test ^ crc);
return(1);
}
