STM32 NUCLEO64: PWM has no output

Question

I'm using STM32F303 NUCLEO64. I used CubeIDE to auto generate the code. The program is running Coz I can see the printf() is updating via SWO. I have added 1 sec delay after GPIO and TIM3 initalization. And I have started PWM by using this code:

HAL_Delay(1000);
HAL_TIMEx_PWMN_Start(&htim3, TIM_CHANNEL_3);

However, there is no PWM waveform from PB0. The complete code is here.

#include "main.h"
#include "stdio.h"

TIM_HandleTypeDef htim3;
void SystemClock_Config(void);
static void MX_GPIO_Init(void);
static void MX_TIM3_Init(void);

uint8_t counter = 0;

int _write(int file, char *ptr, int len)
{
  int i=0;
  for(i=0 ; i<len ; i++)
    ITM_SendChar((*ptr++));
  return len;
}


int main(void)
{
  HAL_Init();
  SystemClock_Config();
  MX_GPIO_Init();
  MX_TIM3_Init();
  HAL_Delay(1000);
  HAL_TIMEx_PWMN_Start(&htim3, TIM_CHANNEL_3);
  while (1)
  {
    counter++;
    printf("counter = %d \n", counter);
    HAL_Delay(100);
  }
}


void SystemClock_Config(void)
{
  RCC_OscInitTypeDef RCC_OscInitStruct = {0};
  RCC_ClkInitTypeDef RCC_ClkInitStruct = {0};
  RCC_PeriphCLKInitTypeDef PeriphClkInit = {0};

  RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSI;
  RCC_OscInitStruct.HSIState = RCC_HSI_ON;
  RCC_OscInitStruct.HSICalibrationValue = RCC_HSICALIBRATION_DEFAULT;
  RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;
  RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_HSI;
  RCC_OscInitStruct.PLL.PLLMUL = RCC_PLL_MUL9;
  RCC_OscInitStruct.PLL.PREDIV = RCC_PREDIV_DIV1;
  if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK)
  {
    Error_Handler();
  }

  RCC_ClkInitStruct.ClockType = RCC_CLOCKTYPE_HCLK|RCC_CLOCKTYPE_SYSCLK
                              |RCC_CLOCKTYPE_PCLK1|RCC_CLOCKTYPE_PCLK2;
  RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_PLLCLK;
  RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1;
  RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV2;
  RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV1;

  if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_2) != HAL_OK)
  {
    Error_Handler();
  }
  PeriphClkInit.PeriphClockSelection = RCC_PERIPHCLK_TIM34;
  PeriphClkInit.Tim34ClockSelection = RCC_TIM34CLK_HCLK;
  if (HAL_RCCEx_PeriphCLKConfig(&PeriphClkInit) != HAL_OK)
  {
    Error_Handler();
  }
}


static void MX_TIM3_Init(void)
{
  TIM_ClockConfigTypeDef sClockSourceConfig = {0};
  TIM_MasterConfigTypeDef sMasterConfig = {0};
  TIM_OC_InitTypeDef sConfigOC = {0};

  htim3.Instance = TIM3;
  htim3.Init.Prescaler = 0;
  htim3.Init.CounterMode = TIM_COUNTERMODE_UP;
  htim3.Init.Period = 65535;
  htim3.Init.ClockDivision = TIM_CLOCKDIVISION_DIV1;
  htim3.Init.AutoReloadPreload = TIM_AUTORELOAD_PRELOAD_ENABLE;
  if (HAL_TIM_Base_Init(&htim3) != HAL_OK)
  {
    Error_Handler();
  }
  sClockSourceConfig.ClockSource = TIM_CLOCKSOURCE_INTERNAL;
  if (HAL_TIM_ConfigClockSource(&htim3, &sClockSourceConfig) != HAL_OK)
  {
    Error_Handler();
  }
  if (HAL_TIM_PWM_Init(&htim3) != HAL_OK)
  {
    Error_Handler();
  }
  sMasterConfig.MasterOutputTrigger = TIM_TRGO_RESET;
  sMasterConfig.MasterSlaveMode = TIM_MASTERSLAVEMODE_DISABLE;
  if (HAL_TIMEx_MasterConfigSynchronization(&htim3, &sMasterConfig) != HAL_OK)
  {
    Error_Handler();
  }
  sConfigOC.OCMode = TIM_OCMODE_PWM1;
  sConfigOC.Pulse = 26214;
  sConfigOC.OCPolarity = TIM_OCPOLARITY_HIGH;
  sConfigOC.OCFastMode = TIM_OCFAST_DISABLE;
  if (HAL_TIM_PWM_ConfigChannel(&htim3, &sConfigOC, TIM_CHANNEL_3) != HAL_OK)
  {
    Error_Handler();
  }
  HAL_TIM_MspPostInit(&htim3);

}


static void MX_GPIO_Init(void)
{
  __HAL_RCC_GPIOB_CLK_ENABLE();
  __HAL_RCC_GPIOA_CLK_ENABLE();

}


void Error_Handler(void)
{
  __disable_irq();
  while (1)
  {
  }
}

#ifdef  USE_FULL_ASSERT
void assert_failed(uint8_t *file, uint32_t line)
{

}
#endif

Code to Config GPIO

void HAL_TIM_MspPostInit(TIM_HandleTypeDef* htim)
{
  GPIO_InitTypeDef GPIO_InitStruct = {0};
  if(htim->Instance==TIM3)
  {
    __HAL_RCC_GPIOB_CLK_ENABLE();
    GPIO_InitStruct.Pin = GPIO_PIN_0;
    GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;
    GPIO_InitStruct.Pull = GPIO_NOPULL;
    GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
    GPIO_InitStruct.Alternate = GPIO_AF2_TIM3;
    HAL_GPIO_Init(GPIOB, &GPIO_InitStruct);
  }
}

You haven't got any code at all to configure any pins. You need to put the GPIO into alternate function mode to connect it to the timer. As it appears you are a beginner I would suggest reading through the various example projects that come with the STM32 cube package first. — Tom V, Oct 13 '22 at 08:19
Hi @Tom V, thanks for your help. Yes, I'm a beginner. I actually have the code to config GPIO. I just forgot to include it in above post. — Steven Wang, Oct 13 '22 at 09:39
It seems like my PWM starts in code, and I'm 100% sure that I'm testing the correct pin. But there is no PWM signal. `if(HAL_TIMEx_PWMN_Start(&htim3, TIM_CHANNEL_3) != HAL_OK){ printf("Error\n"); HAL_Delay(2000); }else{ printf("PWM started\n"); HAL_Delay(2000); }` — Steven Wang, Oct 13 '22 at 12:00

score 0 · Answer 1 · answered Oct 17 '22 at 10:30

For some reason your setup is configuring PB0 as GPIO_AF2_TIM3. According to the datasheet (DS9773) this equates to TIM1_CH2N, which is not what you want.

I think you need to configure PB0 as GPIO_AF1_TIM3, which is TIM3_CH3.

I don't have this Nucleo board, but I created a project for it in CubeIDE and configured TIM3 for PWM output on channel 3, and it auto-generated code that configured PB0 as GPIO_AF1_TIM3.

STM32 NUCLEO64: PWM has no output

1 Answers1