Cannot start to count up TIM3 in PWM generation mode

[HMasu.1]

I use STM32MP151CAA3 mounted on my own board.

I want to start to count up TIM3 in PWM generation mode in Cortex-M4.

I have written following code, However, ​TIM3 doesn't start to count up (After Line 56, TIM3_CNT value doesn't change at all).

In this code, PB04 port is used as PWM output port.

void TIM3_Count_Start(void)
{
	TIM_HandleTypeDef m_handleTim3;
	TIM_OC_InitTypeDef sConfigOC;
	TIM_SlaveConfigTypeDef sSlaveConfig;
	TIM_MasterConfigTypeDef sMasterConfig;
	GPIO_InitTypeDef GPIO_InitStruct;
 
	/* Peripheral clock enable */
        __TIM3_CLK_ENABLE();
  
        GPIO_InitStruct.Pin = GPIO_PIN_4;
        GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;
        GPIO_InitStruct.Pull = GPIO_NOPULL;
        GPIO_InitStruct.Speed = GPIO_SPEED_LOW;
        GPIO_InitStruct.Alternate = GPIO_AF2_TIM3;
        HAL_GPIO_Init(GPIOB, &GPIO_InitStruct);
 
	m_handleTim3.Instance = TIM3;
	m_handleTim3.Init.Prescaler = 0;
	m_handleTim3.Init.CounterMode = TIM_COUNTERMODE_UP;
	m_handleTim3.Init.Period = 0;
	m_handleTim3.Init.ClockDivision = TIM_CLOCKDIVISION_DIV1;
	HAL_TIM_Base_Init(&m_handleTim3);
 
	HAL_TIM_PWM_Init(&m_handleTim3);
 
	sConfigOC.OCMode = TIM_OCMODE_PWM1;
	sConfigOC.Pulse = 0xFFFF;
	sConfigOC.OCPolarity = TIM_OCPOLARITY_HIGH;
	sConfigOC.OCFastMode = TIM_OCFAST_DISABLE;
	HAL_TIM_PWM_ConfigChannel(&m_handleTim3, &sConfigOC, TIM_CHANNEL_1);
 
	sSlaveConfig.SlaveMode = TIM_SLAVEMODE_EXTERNAL1;
	sSlaveConfig.InputTrigger = TIM_TS_ITR0;
	HAL_TIM_SlaveConfigSynchronization(&m_handleTim3, &sSlaveConfig);
 
	sMasterConfig.MasterOutputTrigger = TIM_TRGO_RESET;
	sMasterConfig.MasterSlaveMode = TIM_MASTERSLAVEMODE_DISABLE;
	HAL_TIMEx_MasterConfigSynchronization(&m_handleTim3, &sMasterConfig);
 
	TIM3->PSC = 399;
	TIM3->ARR = 49;
 
	TIM3->CCR1 = 0xFFFF;
 
	TIM3->CR1 |= 0x0080;
 
	TIM3->EGR |= TIM_EGR_UG;
 
	TIM3->CCER |= 0x0001;
 
	TIM3->SR = 0;
	TIM3->DIER |= 0x0001;
 
	TIM3->CR1 |= 0x0001;		/* TIM3 Count Start */
}

Is there any missing in above code?

Best Regards.

H. Masuda

[Michal Dudka]

To what value it should count ? ;)

[HMasu.1]

@Michal Dudka​ 

I expect that TIM3_CNT counts up from 0 to TIM3_ARR value (and returns to 0, and counts up to TIM3_ARR value again).

When I used to use STM32F437ZI, TIM3​_CNT counts up in PWM generation mode, so I expect it to behave similarly.

H. Masuda.​

[Michal Dudka]

Right... sorry i've overlooked second part of your code. I've read your "period" and "prescaler" settings in HAL timer init part. One do not expect that you initialize/config timer twice consecutively (why the hell ?). Rewrite your code to some familiar form (use HAL or LL or use proper bit macros like "TIM_EGR_UG"). Nobody have time to list thru datasheet and counts bit by bit to read your timer configuration. I am not familiar with MPUs but i would look into RCC configuration first ... check if timer clock is enabled.

[TDK · Accepted solution]

> sSlaveConfig.SlaveMode = TIM_SLAVEMODE_EXTERNAL1;

If you want the timer to run by itself, set this to TIM_SLAVEMODE_DISABLE. Otherwise, you need to ensure there is a external clock source driving it.

[HMasu.1]

Hi @Michal Dudka​ 

Thank you for your answer.

I am going to use it as an example.

And, I take care to ask questions that are easier to understand.​

H.Masuda

[HMasu.1]

Hi @TDK​ 

I tried to use another timer as prescaler, but the settings to do that were wrong.

Your advice solved the problem.

Thank you very much.

H. Masuda