Not being able to enable PWM using the HAL TIM library on stm32f0

Question

The goal is to use the PWM feature of stm32 HAL TIM libraries to light up 4 leds on pins 0, 1, 4 and 5

I have generated the following code using CubeMX:

void MX_TIM3_Init(void)
{
 TIM_ClockConfigTypeDef sClockSourceConfig;
 TIM_MasterConfigTypeDef sMasterConfig;
 TIM_OC_InitTypeDef sConfigOC;
 htim3.Instance = TIM3;
 htim3.Init.Prescaler = 32;
 htim3.Init.CounterMode = TIM_COUNTERMODE_UP;
 htim3.Init.Period = 1000;
 htim3.Init.ClockDivision = TIM_CLOCKDIVISION_DIV1;
 HAL_TIM_Base_Init(&htim3);
 sClockSourceConfig.ClockSource = TIM_CLOCKSOURCE_INTERNAL;
 HAL_TIM_ConfigClockSource(&htim3, &sClockSourceConfig);
 HAL_TIM_PWM_Init(&htim3);
 sMasterConfig.MasterOutputTrigger = TIM_TRGO_RESET;
 sMasterConfig.MasterSlaveMode = TIM_MASTERSLAVEMODE_DISABLE;
 HAL_TIMEx_MasterConfigSynchronization(&htim3, &sMasterConfig);
 sConfigOC.OCMode = TIM_OCMODE_PWM1;
 sConfigOC.Pulse = 500;
 sConfigOC.OCPolarity = TIM_OCPOLARITY_HIGH;
 sConfigOC.OCFastMode = TIM_OCFAST_DISABLE;
 HAL_TIM_PWM_ConfigChannel(&htim3, &sConfigOC, TIM_CHANNEL_1);
 HAL_TIM_PWM_ConfigChannel(&htim3, &sConfigOC, TIM_CHANNEL_2);
 HAL_TIM_PWM_ConfigChannel(&htim3, &sConfigOC, TIM_CHANNEL_3);
 HAL_TIM_PWM_ConfigChannel(&htim3, &sConfigOC, TIM_CHANNEL_4);
 HAL_TIM_MspPostInit(&htim3); 
}

This initiates the timer.

void HAL_TIM_MspPostInit(TIM_HandleTypeDef* htim)
{ 
 GPIO_InitTypeDef GPIO_InitStruct;
 if(htim->Instance==TIM3)
 {
 /* USER CODE BEGIN TIM3_MspPostInit 0 */
 /* USER CODE END TIM3_MspPostInit 0 */
 /**TIM3 GPIO Configuration 
 PB0 ------> TIM3_CH3
 PB1 ------> TIM3_CH4
 PB4 ------> TIM3_CH1
 PB5 ------> TIM3_CH2 
 */
 GPIO_InitStruct.Pin = GPIO_PIN_0|GPIO_PIN_1|GPIO_PIN_4|GPIO_PIN_5;
 GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;
 GPIO_InitStruct.Pull = GPIO_NOPULL;
 GPIO_InitStruct.Speed = GPIO_SPEED_LOW;
 GPIO_InitStruct.Alternate = GPIO_AF1_TIM3;
 HAL_GPIO_Init(GPIOB, &GPIO_InitStruct);
 /* USER CODE BEGIN TIM3_MspPostInit 1 */
 /* USER CODE END TIM3_MspPostInit 1 */
 }
}

This initiates the GPIO pins for PWM.

Also the clock is enabled in the HAL_TIM_Base_MspInit callback function using __TIM3_CLK_ENABLE().

In the main.c file I have added the following code after all initializations, to start the base timer and PWM:

HAL_TIM_Base_Start(&htim3);
HAL_TIM_PWM_Start(&htim3,TIM_CHANNEL_ALL);

Now after running this code on the stm32f070cb the LEDs do not light up at least slightly.

I have tried changing the compare values CCRx. Also the GPIO pins work since I can use HAL_GPIO_WritePin to turn on the LEDs. Besides that I found out that the counter is actually running between 0 and 1000 using the __HAL_TIM_GetCounter macro. It just seems that the LEDs are not reacting to the compare values.

Did someone have a similar problem or have some hints to go from here?

Answer 1

Thanks to a kind suggestion I was able to get the PWM working using the TIM_PWMOutput example under the STM32F0 CubeMX firmware:

STM32Cube_FW_F0_V1.5.0\Projects\STM32F0308Discovery\Examples\TIM\TIM_PWMOutput

I have now solved my problem using the code from the example. Though I am not sure where it is different from the code generated by CubeMX.

Answer 2

I recently experienced the same problem with you. Modify the prototype of function HAL_TIM_MspPostInit(void) as below :

/**/
static void HAL_TIM_MspPostInit(void)
{ 
 GPIO_InitTypeDef GPIO_InitStruct;
 /**TIM3 GPIO Configuration 
 PB0 ------> TIM3_CH3
 PB1 ------> TIM3_CH4
 PB4 ------> TIM3_CH1
 PB5 ------> TIM3_CH2 
 */
 GPIO_InitStruct.Pin = GPIO_PIN_0|GPIO_PIN_1|GPIO_PIN_4|GPIO_PIN_5;
 GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;
 GPIO_InitStruct.Pull = GPIO_NOPULL;
 GPIO_InitStruct.Speed = GPIO_SPEED_LOW;
 GPIO_InitStruct.Alternate = GPIO_AF1_TIM3;
 HAL_GPIO_Init(GPIOB, &GPIO_InitStruct);
}

and use the function as HAL_TIM_MspPostInit(); in the main function. Basically, this is same with MX_GPIO_Init function you may find in the HAL libraries. I cannot understand why they added another functions to initiate GPIOs for PWM in particular.