Unstable work on STM32H743IIT6 mcu.

[PYoda.1]

Hello community!

My mcu is STM32H743IIT6 tqsp176 from blue waveshare board. I create a new project from Cube with HAL. Then I make the simplest flashing cycle of the LED:

volatile unsigned long x = 0;
 
  while (1)
  {
		while (x++ < 2000000) {}
		x = 0;
		HAL_GPIO_WritePin(GPIOI, GPIO_PIN_0, GPIO_PIN_RESET);
	  
		while (x++ < 2000000) {}
		x = 0;
		HAL_GPIO_WritePin(GPIOI, GPIO_PIN_0, GPIO_PIN_SET);
  }

Any changes in code result in accidental change in frequency and DUTY CYCLE. For example:

1) When I make variable x global or local.

2) When i put beforce blink cycle this line HAL_GPIO_WritePin(GPIOI, GPIO_PIN_0, GPIO_PIN_RESET);

3) When i add new variable such Y to cycle:

volatile unsigned long x = 0;
volatile unsigned long y = 0;
while (1)
{
		 while (x++ < 2000000) {}
		y = x;
		x = 0;
		HAL_GPIO_WritePin(GPIOI, GPIO_PIN_0, GPIO_PIN_RESET);
	  
		while (x++ < 2000000) {}
		y = x;
		x = 0;
		HAL_GPIO_WritePin(GPIOI, GPIO_PIN_0, GPIO_PIN_SET);
  }

In this case frequesy change in random range. Can get X times higher, and can get X times lower. Duty cycle can become 10% / 90% or 30% / 70% and other.

4) When i put some code before this cycle frequency and duty cycle also change!!!

 

5) Even just when I move some code in places!!!

volatile unsigned long y = 0;  // <<<<<<<  declare first
volatile unsigned long x = 0;
 
while (1)
  {
		x = 0; // << move x here
		while (x++ < 2000000) {}
		y = x;
		
		HAL_GPIO_WritePin(GPIOI, GPIO_PIN_0, GPIO_PIN_RESET);
	  
		x = 0; // << move x here
		while (x++ < 2000000) {}
		y = x;
		
		HAL_GPIO_WritePin(GPIOI, GPIO_PIN_0, GPIO_PIN_SET);
  }

 

Absolutely any changes in code result in accidental change in frequency and DUTY CYCLE.

I try mcu work on HSE, PLL, HSI... there is no difference. I try keil compiler v5 & v6.. no difference. I try to create project without CUBE and HAL ... there is no difference. I try any dividers and clocks ... there is no difference.

MCU broken?

[PYoda.1]

Today I run hardware PWM with TIMER3 CH1. It 's impossible, but the problem remains!

I excluded RCC config from system and now MCU work on HSI 64 MHz. Startup file from keil not modified. Are 2 running timers in system. TIM12 with interrupt and TIM3 without interrupt.

	RCC->APB1LENR |= RCC_APB1LENR_TIM12EN;
	
	TIM12->ARR = 10000;
	TIM12->DIER |= TIM_DIER_UIE;
	TIM12->PSC = 1000;
	TIM12->CR1 |= TIM_CR1_URS;
	TIM12->CR1 |= TIM_CR1_CEN;
	
 
	RCC->APB1LENR |= RCC_APB1LENR_TIM3EN;
	
	TIM3->ARR    = 20000;
	TIM3->PSC    = 1000;
	TIM3->CR1   |= TIM_CR1_URS;
	TIM3->CR1   |= TIM_CR1_ARPE;
	TIM3->CCMR1 |= TIM_CCMR1_OC1M_1 | TIM_CCMR1_OC1M_2 | TIM_CCMR1_OC1PE; 
	TIM3->CCR1   = 10000;
	TIM3->EGR   |= TIM_EGR_UG;
	TIM3->CCER  |= TIM_CCER_CC1E;
	TIM3->CR1  |= TIM_CR1_CEN;
 
	NVIC_EnableIRQ(TIM8_BRK_TIM12_IRQn);
 
	while (1) {}

And interrupt for TIM12

void TIM8_BRK_TIM12_IRQHandler (void)
{
	if (TIM12->SR & 1UL)
	{
		TIM12->SR = 0;
		
		if (flag)
		{
			LED_ON;
			flag = 0;
		}
		else
		{
			LED_OFF;
			flag = 1;
		}
	}
}

In global visibility area:

#define LED_ON  GPIOI->BSRR |= (1UL << 16)
#define LED_OFF GPIOI->BSRR |= (1UL <<  0)
volatile unsigned char flag = 0;

When i put LED_ON while (1) {} frequency and duty cycle are broken down.

[Pavel A.]

> That 's the whole code. There is nothing any more. 

Not quite true... There should be a startup file (.s). It can pull in SystemInit() etc.

How do you build and debug? Which IDE? Debugger?

 -- pa

Updated:

Ah sorry, I see. It's Keil. Compiler v5 or v6?

[Tesla DeLorean]

PSC and ARR are programmed as N-1 for N states, zero thru N-1

TIM12->ARR = 10000 - 1;

TIM12->PSC = 1000 - 1;

Divide by 10,000,000

[berendi]

> When i put LED_ON while (1) {} frequency and duty cycle are broken down.

1. Measure the supply voltage on the pins while the led is on / off.
2. Measure the current drawn by the led if possible, or the value of the series resistor connected to it (while not powered), and the voltage dropped on the series resistor (while powered).
3. Put the HSI clock on the MCO pin, measure it there.
4. Which board is it? One of these? https://www.waveshare.com/wiki/OpenH743I-C ?
5. How are the onboard jumpers set?

[PYoda.1]

I tried both compilers (v5 v6).

[PYoda.1]

1) 3.3V

2) 600 Ohm. But i used another pins without leds. They have exactly the same problem.

3) 4.347 MHz with prescaler /15

4) Right. It is waveshare blue core devboard.

5) Only one jumper set (VREF -> 3.3V)

[berendi]

4.347 MHz * 15 = 65.205, it looks quite bad. Datasheet says 63.7 to 64.3.

Tried your code with a few changes on a Nucleo-743ZI2 board. No clock setup, running on HSI. Much better results here.

Using timer channel 3 to blink the led on PB0, -1 from ARR and PSC as Clive1 suggested.

void led_red(int x) {
	GPIOB->BSRR = x ? (1u << 14u) : (1u << 30u);
}
void led_yellow(int x) {
	GPIOE->BSRR = x ? (1u << 1u) : (1u << 17u);
}
 
volatile int flag;
#define LED_ON led_yellow(1)
#define LED_OFF led_yellow(0)
void TIM8_BRK_TIM12_IRQHandler (void)
{
	if (TIM12->SR & 1UL)
	{
		TIM12->SR = 0;
		if(flag)
		{
			LED_ON;
			flag = 0;
		}
		else
		{
			LED_OFF;
			flag = 1;
		}
	}
}
 
int main() {
	RCC->AHB4ENR  |= RCC_AHB4ENR_GPIOBEN | RCC_AHB4ENR_GPIOEEN;
	RCC->AHB4ENR;
	RCC->APB1LENR |= RCC_APB1LENR_TIM12EN | RCC_APB1LENR_TIM3EN;
	RCC->APB1LENR;
	led_red(1);
	GPIOB->AFR[0] = 2 << 0; // PB0 AF2 TIM3_CH3
	GPIOB->MODER &= ~((2u << 28u) | (1u << 0u)); // red led output, green AF
	GPIOE->MODER &= ~(2u << 2u); // yellow led output
 
	TIM12->ARR   = 10000-1;
	TIM12->DIER |= TIM_DIER_UIE;
	TIM12->PSC   = 1000-1;
	TIM12->CR1  |= TIM_CR1_URS;
	TIM12->CR1  |= TIM_CR1_CEN;
	TIM3->ARR    = 20000-1;
	TIM3->PSC    = 1000-1;
	TIM3->CR1   |= TIM_CR1_URS;
	TIM3->CR1   |= TIM_CR1_ARPE;
//	TIM3->CCMR1 |= TIM_CCMR1_OC1M_1 | TIM_CCMR1_OC1M_2 | TIM_CCMR1_OC1PE;
//	TIM3->CCR1   = 10000;
	TIM3->CCMR2 |= TIM_CCMR2_OC3M_1 | TIM_CCMR2_OC3M_2 | TIM_CCMR2_OC3PE;
	TIM3->CCR3   = 10000-1;
	TIM3->EGR   |= TIM_EGR_UG;
//	TIM3->CCER  |= TIM_CCER_CC1E;
	TIM3->CCER  |= TIM_CCER_CC3E;
	TIM3->CR1   |= TIM_CR1_CEN;
	NVIC_EnableIRQ(TIM8_BRK_TIM12_IRQn);
	while(1)
		;
}

Frequency measured on both outputs: 3.209 - 3.211 Hz, period 311.4 - 311.6 ms.

Then played around a bit.

Setting the system clock to 480 MHz, timer clocks 240 MHz (clock setup in my answer here), still based on HSI:

Frequency measured on both outputs: 12.03 Hz, period 83.12 ms.

Setting system clock to 480 MHz based on HSI:

Frequency measured on both outputs: 11.95 Hz, period 83.68 ms. I might have overlooked something here.

[PYoda.1]

My logic analyzer says than frequency between 4.16666 (62,4 MHz) and 4.347 (65,55 MHz). I dont have an oscilloscope.