STM32C011. Cant run sysclk from LSI.

[SHDK2000]

Im trying to run SYSCLK from LSI on a STM32C011. But it appears as if the MCU is not running. I cant see anything in the datasheet that says the clock cant be used and it can be routed fine in the clock configurator. Am I missing something in the datasheet or does the HAL not support it?

[mƎALLEm]

Hello,

Nothing prevents you using LSI as a clock source for the system clock. From RM0490:

CubeMx:

Are you using CubeMx for the code generation or are you coding the system clock config yourself?

" But it appears as if the MCU is not running" 

-> how do you know? what are the symptoms? how you did you debug that?

How to write your question to maximize your chances to find a solution

[SHDK2000]

I have set the clock as shown. I have verified that I get no clock out when I use LSI. I also have a serial port configured. Again, everything works fine when using HSI as source for SYSCLK. Nothing happens when I use LSI.

[Andrew Neil]

This was in response to posts about unmarking a solution which have since been removed.

---

See:

https://community.st.com/t5/community-guidelines/help-others-to-solve-their-issues/ta-p/575256#:~:text=If%20you%20accidentally%20choose%20the%20wrong%20post%20as%20the%20solution%2C%20you%20can%20revert%20this%20action%20by%20clicking%C2%A0Not%20the%20Solution

PS:

See also: Unmark Solution is too hard to find.

[SHDK2000]

I have used the following clock setting.

I use the MCO to verify if SYSCLK is running. I also have a serial port to confirm activity.

It all works fine when using HSI. I doesnt work with LSI. It cant even run an endless loop toggling an IO.

[mƎALLEm]

"I doesnt work with LSI" does tell nothing. 

1- How did you debug that? 

2- Share your ioc file

[SHDK2000]

Sorry.

I get MCO with HSI.

I do not get MCO with LSI.

"I use the MCO to verify if SYSCLK is running." is what I said. Does that not tell anything? I would normally use it to validate if my MCU/SYSCLK is running.

[mƎALLEm]

Did you run a debug session to find what is going on in your code? is it blocking anywhere in your code?

[mfgkw]

Even when I do not understand why you want to do it...

What makes you believe the MCU does not run at all?

Maybe it is just really slow. LSI is ~32kHz or 0.032 MHz, while using HSI we talk about 48/n MHz.

[SHDK2000]

I have attached the ioc file. 

I add the following code:

while (1)
  {
	  HAL_UART_Transmit(&huart2, "Hello\n\r", 7, 1000);
	  HAL_Delay(1000);
    /* -- Sample board code for User push-button in interrupt mode ---- */

    /* USER CODE END WHILE */

    /* USER CODE BEGIN 3 */
  }

Works fine with HSI.
Nothing happens with LSI.