cancel
Showing results for 
Search instead for 
Did you mean: 

looking for help with a pwm

ulao
Associate III

I have this code that bring a line up for 5us and down for 20. I want to invert it. I thought the first part of the code was a time base loop and the second was also a timer base loop. but one setting effects the other. If I use htim4.Init.Period = 250; // for 100 kHz for the first I get 5us/5us but I'm not following setting the second .

static void MX_TIM4_Init(void)
{
 
  /* USER CODE BEGIN TIM4_Init 0 */
 
  /* USER CODE END TIM4_Init 0 */
 
  TIM_ClockConfigTypeDef sClockSourceConfig = {0};
  TIM_MasterConfigTypeDef sMasterConfig = {0};
  TIM_OC_InitTypeDef sConfigOC = {0};
 
  /* USER CODE BEGIN TIM4_Init 1 */
 
  /* USER CODE END TIM4_Init 1 */
  htim4.Instance = TIM4;
  htim4.Init.Prescaler = 10;
  htim4.Init.CounterMode = TIM_COUNTERMODE_DOWN;
  htim4.Init.Period = 500;  // for 50 kHz
//  htim4.Init.Period = 250;  // for 100 kHz
  htim4.Init.ClockDivision = TIM_CLOCKDIVISION_DIV1;
  htim4.Init.AutoReloadPreload = TIM_AUTORELOAD_PRELOAD_ENABLE;
  if (HAL_TIM_Base_Init(&htim4) != HAL_OK)
  {
    Error_Handler();
  }
  sClockSourceConfig.ClockSource = TIM_CLOCKSOURCE_INTERNAL;
  if (HAL_TIM_ConfigClockSource(&htim4, &sClockSourceConfig) != HAL_OK)
  {
    Error_Handler();
  }
  if (HAL_TIM_PWM_Init(&htim4) != HAL_OK)
  {
    Error_Handler();
  }
  sMasterConfig.MasterOutputTrigger = TIM_TRGO_RESET;
  sMasterConfig.MasterSlaveMode = TIM_MASTERSLAVEMODE_DISABLE;
  if (HAL_TIMEx_MasterConfigSynchronization(&htim4, &sMasterConfig) != HAL_OK)
  {
    Error_Handler();
  }
  sConfigOC.OCMode = TIM_OCMODE_PWM1;
//  sConfigOC.Pulse = 250;		// for 50 kHz
  sConfigOC.Pulse = 125;		// for 100 kHz
  sConfigOC.OCPolarity = TIM_OCPOLARITY_HIGH;
  sConfigOC.OCFastMode = TIM_OCFAST_ENABLE;
  if (HAL_TIM_PWM_ConfigChannel(&htim4, &sConfigOC, TIM_CHANNEL_2) != HAL_OK)
  {
    Error_Handler();
  }
  /* USER CODE BEGIN TIM4_Init 2 */
  /*##-3- Start PWM signal generation in DMA mode ############################*/
  if(HAL_TIM_PWM_Start(&htim4, TIM_CHANNEL_2) != HAL_OK)
  {
    /* Starting PWM generation Error */
    Error_Handler();
  }
 
  /* USER CODE END TIM4_Init 2 */
  HAL_TIM_MspPostInit(&htim4);
 
}

2 REPLIES 2
ulao
Associate III

ah, didnt realize there was a polarity. ---> sConfigOC.OCPolarity = TIM_OCPOLARITY_LOW;

S.Ma
Principal

Always read entirely the peripheral chapter of the reference manual, it is a good return of time investment

...