How to access STM32H753 CRC unit

[HigerY]

Hello,

Recently I try to use the CRC unit insde stm32h753vih6 to do the crc calculation. According to the spec(RM0433), I tried to read/write the registers defined in chapter21. But all the five CRC related registers(CRC_DR, CRC_IDR, CRC_CR, CRC_INIT, CRC_POL) are zero and cannot be changed.

addr:0x58024c00 value:0x0
addr:0x58024c04 value:0x0
addr:0x58024c08 value:0x0
addr:0x58024c0c value:0x0
addr:0x58024c10 value:0x0  //CRC_POL should have 0x04c11db7 as the default value

I have tried to reset CRC unit through CRC_CR bit0. But the issue still exists.

Does CRC module need extra configuration so that it can be used?

[HigerY]

In the beginning, I followed the following example to do the crc calculation but always got the zero crc value. Then I tried to access its registers and then got the issue described in my post.

https://github.com/STMicroelectronics/STM32CubeH7/blob/master/Projects/STM32H743I-EVAL/Examples/CRC/CRC_Example/Src/main.c

[HigerY · Accepted solution]

I think that I just find out the rootcause. I didn't call __HAL_RCC_CRC_CLK_ENABLE() to enable the CRC clock. After doing that, I can access the CRC related registers.