clock setting, STM32H750

[pk84]

Hello,

I have two different clock setting and only one of them works - but I have no idea why?

The only difference is the PLLM and PLLN value:

 RCC_OscInitStruct.PLL.PLLM = 25; // 5 NOT OK

 RCC_OscInitStruct.PLL.PLLN = 432; // 160 NOT OK

Would appreciate any hints...

See clock seting below, I have a 25MHz ext. Crystal:

NOT working clock setting:

CC_ClkInitTypeDef RCC_ClkInitStruct;
 RCC_OscInitTypeDef RCC_OscInitStruct;
 HAL_StatusTypeDef ret = HAL_OK;
 
 /*!< Supply configuration update enable */
 HAL_PWREx_ConfigSupply(PWR_LDO_SUPPLY); /* PWR set to LDO for the STM32H750B-DISCO board */
 
 /* The voltage scaling allows optimizing the power consumption when the device is
 clocked below the maximum system frequency, to update the voltage scaling value
 regarding system frequency refer to product datasheet. */
 __HAL_PWR_VOLTAGESCALING_CONFIG(PWR_REGULATOR_VOLTAGE_SCALE1);
 
 while(!__HAL_PWR_GET_FLAG(PWR_FLAG_VOSRDY)) {}
 
 /* Enable HSE Oscillator and activate PLL with HSE as source */
 RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSE;
 RCC_OscInitStruct.HSEState = RCC_HSE_ON;
 RCC_OscInitStruct.HSIState = RCC_HSI_OFF;
 RCC_OscInitStruct.CSIState = RCC_CSI_OFF;
 RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;
 RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_HSE;
 
 RCC_OscInitStruct.PLL.PLLM = 5;
 RCC_OscInitStruct.PLL.PLLN = 160;
 RCC_OscInitStruct.PLL.PLLFRACN = 0;
 RCC_OscInitStruct.PLL.PLLP = 2;
 RCC_OscInitStruct.PLL.PLLR = 2;
 RCC_OscInitStruct.PLL.PLLQ = 4;
 
 RCC_OscInitStruct.PLL.PLLVCOSEL = RCC_PLL1VCOWIDE;
 RCC_OscInitStruct.PLL.PLLRGE = RCC_PLL1VCIRANGE_2;
 ret = HAL_RCC_OscConfig(&RCC_OscInitStruct);
 if(ret != HAL_OK)
 {
 Error_Handler();
 }
 
 /* Select PLL as system clock source and configure bus clocks dividers */
 RCC_ClkInitStruct.ClockType = (RCC_CLOCKTYPE_SYSCLK | RCC_CLOCKTYPE_HCLK | RCC_CLOCKTYPE_D1PCLK1 | RCC_CLOCKTYPE_PCLK1 | \
 RCC_CLOCKTYPE_PCLK2 | RCC_CLOCKTYPE_D3PCLK1);
 
 RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_PLLCLK;
 RCC_ClkInitStruct.SYSCLKDivider = RCC_SYSCLK_DIV1;
 RCC_ClkInitStruct.AHBCLKDivider = RCC_HCLK_DIV2;
 RCC_ClkInitStruct.APB3CLKDivider = RCC_APB3_DIV2;
 RCC_ClkInitStruct.APB1CLKDivider = RCC_APB1_DIV2;
 RCC_ClkInitStruct.APB2CLKDivider = RCC_APB2_DIV2;
 RCC_ClkInitStruct.APB4CLKDivider = RCC_APB4_DIV2;
 ret = HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_4);
 if(ret != HAL_OK)
 {
 Error_Handler();
 }

Working clock setting:

CC_ClkInitTypeDef RCC_ClkInitStruct;
 RCC_OscInitTypeDef RCC_OscInitStruct;
 HAL_StatusTypeDef ret = HAL_OK;
 
 /*!< Supply configuration update enable */
 HAL_PWREx_ConfigSupply(PWR_LDO_SUPPLY); /* PWR set to LDO for the STM32H750B-DISCO board */
 
 /* The voltage scaling allows optimizing the power consumption when the device is
 clocked below the maximum system frequency, to update the voltage scaling value
 regarding system frequency refer to product datasheet. */
 __HAL_PWR_VOLTAGESCALING_CONFIG(PWR_REGULATOR_VOLTAGE_SCALE1);
 
 while(!__HAL_PWR_GET_FLAG(PWR_FLAG_VOSRDY)) {}
 
 /* Enable HSE Oscillator and activate PLL with HSE as source */
 RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSE;
 RCC_OscInitStruct.HSEState = RCC_HSE_ON;
 RCC_OscInitStruct.HSIState = RCC_HSI_OFF;
 RCC_OscInitStruct.CSIState = RCC_CSI_OFF;
 RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;
 RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_HSE;
 
 RCC_OscInitStruct.PLL.PLLM = 25;
 RCC_OscInitStruct.PLL.PLLN = 432;
 RCC_OscInitStruct.PLL.PLLFRACN = 0;
 RCC_OscInitStruct.PLL.PLLP = 2;
 RCC_OscInitStruct.PLL.PLLR = 2;
 RCC_OscInitStruct.PLL.PLLQ = 4;
 
 RCC_OscInitStruct.PLL.PLLVCOSEL = RCC_PLL1VCOWIDE;
 RCC_OscInitStruct.PLL.PLLRGE = RCC_PLL1VCIRANGE_2;
 ret = HAL_RCC_OscConfig(&RCC_OscInitStruct);
 if(ret != HAL_OK)
 {
 Error_Handler();
 }
 
 /* Select PLL as system clock source and configure bus clocks dividers */
 RCC_ClkInitStruct.ClockType = (RCC_CLOCKTYPE_SYSCLK | RCC_CLOCKTYPE_HCLK | RCC_CLOCKTYPE_D1PCLK1 | RCC_CLOCKTYPE_PCLK1 | \
 RCC_CLOCKTYPE_PCLK2 | RCC_CLOCKTYPE_D3PCLK1);
 
 RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_PLLCLK;
 RCC_ClkInitStruct.SYSCLKDivider = RCC_SYSCLK_DIV1;
 RCC_ClkInitStruct.AHBCLKDivider = RCC_HCLK_DIV2;
 RCC_ClkInitStruct.APB3CLKDivider = RCC_APB3_DIV2;
 RCC_ClkInitStruct.APB1CLKDivider = RCC_APB1_DIV2;
 RCC_ClkInitStruct.APB2CLKDivider = RCC_APB2_DIV2;
 RCC_ClkInitStruct.APB4CLKDivider = RCC_APB4_DIV2;
 ret = HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_4);
 if(ret != HAL_OK)
 {
 Error_Handler();
 }

[Foued_KH]

Hello @pk84​ ,

I advice you try with STM32CubeMX to set Timing via Clock Configuration. It's more easier for you to manage your clock tree.

For your example :

• Enable the HSE as: Crystal/Ceramic Resonator.
• Choose the external HSE clock and switch to PLL internally.
• Set your desired frequency.

RCC_OscInitStruct.PLL.PLLM = 5; 
RCC_OscInitStruct.PLL.PLLN = 160; 

 

Foued

[pk84]

Thank you. I already use CubeMx (Code is generated from CubeMx).

I forgot to mention what exactly is not working.

It is a simple LED blinking program (see code below) with two LEDs.

One LED on Pin PF10 and the other one on Pin PC13.

If I select 5/160 only the PC13 LED is blinking, if I select 25/432 both LEDs are blinking.

This is very strange for me... I still have no idea about the root cause or how to find it.. :( ??

LED blinking program:

 while (1)
 {
 /* USER CODE END WHILE */
 
 /* USER CODE BEGIN 3 */
	 HAL_Delay(600);
	 //HAL_GPIO_TogglePin(GPIOB, GPIO_PIN_0);
	 //HAL_GPIO_TogglePin(GPIOB, GPIO_PIN_1);
 
 
	 HAL_GPIO_TogglePin(GPIOC, GPIO_PIN_13);
	 //HAL_GPIO_TogglePin(GPIOB, GPIO_PIN_14);
	 //HAL_GPIO_TogglePin(GPIOE, GPIO_PIN_6);
	 HAL_GPIO_TogglePin(GPIOF, GPIO_PIN_10);
 
	 //HAL_Delay(500);
	 //HAL_GPIO_TogglePin(GPIOA, GPIO_PIN_8);
 }

[pk84]

with the Debugger both LEDs seems to work with 5/160...

So do I have a PCB, Layout or Crystal problem??

I used the same (power) circuit diagram as from the STM32H750 Discovery board....

See below video-link of DEBUG with the two different clock settings.

Hope somebody can help me here?

25/432 clock setting (OK - but maybe also not ok??)

https://drive.google.com/file/d/1auRE17ihgOZkdqk6qohLRDti8w7o1hnI/view?usp=share_link

5/160 clock setting (NOT OK)

https://drive.google.com/file/d/1auVbjhQM_t4_ZGWx7c-mFSc364bO0vQO/view?usp=share_link

[LCE]

Well, I don't see anything blinking with 600 ms in any video.

Maybe check your SysTick generation, which is used by HAL_Delay (I think).

But you see that the "working version" runs on a 216 MHz clock, the other version with 400 MHz ?

[pk84]

No hints? Where/How can I get professional support?

[Pavel A.]

> I used the same (power) circuit diagram as from the STM32H750 Discovery board

So your board is not the STM32H750 Discovery? Then what is it?

[pk84]

It is a custom board.

Power circuit, crystal and other "important" settings are according the STM32H750 Disco schematic...

[pk84]

:( ?

[Foued_KH]

Hello @pk84​ ,

The GPIOC and GPIOF are mapped on the same bus and no problems with the STM32H750 Disco

Try to verify your PCB .

Foued

[pk84]

> Well, I don't see anything blinking with 600 ms in any video.

These videos shows the debug mode, below two video links with normal mode

> But you see that the "working version" runs on a 216 MHz clock, the other version with 400 MHz ?

Yes

> Try to verify your PCB .

Phuu, it's a 6-layer, made by a freelancer... where would you start? Measure the clock frequency?

Here the video in normal mode with 5/160 clock setting (D1CPRE = 400 MHz):

https://drive.google.com/file/d/1bgKju-XdIOGF8OOVtqfoF6AWtfhtE2Dg/view?usp=share_link

Here the video in normal mode with 25/432 clock setting (D1CPRE = 216 MHz):

https://drive.google.com/file/d/1bXV0G1ygs-yc_txlSVRaHcNR-42bdoNI/view?usp=share_link

[pk84]

It looks GPIO PF10 is not compatible with clock setting 5/160 (400 MHz)...

GPIO PF10 = blue LED, GPIO PC13 = red LED

Can this be logical?

EDIT: If reduce the frequency from 400 MHz to 300Mhz or lower, the blue LED is slightly visible..

I will measure this GPIO output, strange...

Result: The higher the frequency, the lower the GPIO output voltage... special.

And because the blue LED needs more VF, I see the problem first with the blue LED...

Additional note: I use the STLink/V2 supply (Pin 19)... maybe this is the problem (I thought the supply is rated up to 800mA).