PWM input controlling PWM output

[Roth.Ian]

I have an interface that utilizes inverted PWM and I need a STM32F7 to receive and reply to messages from a controller. The controller sends 64 bit messages, the first 32 bits contains an address and if it matches with the address of the STM32F7, the microcontroller needs to respond with a 32 bit message clocked to the last 32 bits from the controller. I am using tim2 and tim3 to do this with tim2 on the input side generating a trigger for tim3. The problem is that I am using the input capture interrupt (HAL_TIM_IC_CaptureCallback), and I want to set up tim3 for DMA at the end of the 32nd pulse and thus interrupt before the start of 33rd bit. Using the HAL_TIM_PWM_Start_DMA function seems to kick off tim3 instead of waiting for the trigger of the start of the 33rd bit. How do I get the first output pulse to line up with the start of the 33rd input bit?

Here is relevant portion the tim.c generated from STM32CubeMx that I am using:

/* TIM2 init function */

void MX_TIM2_Init(void)

{

 /* USER CODE BEGIN TIM2_Init 0 */

 /* USER CODE END TIM2_Init 0 */

 TIM_ClockConfigTypeDef sClockSourceConfig = {0};

 TIM_SlaveConfigTypeDef sSlaveConfig = {0};

 TIM_IC_InitTypeDef sConfigIC = {0};

 TIM_MasterConfigTypeDef sMasterConfig = {0};

 /* USER CODE BEGIN TIM2_Init 1 */

 /* USER CODE END TIM2_Init 1 */

 htim2.Instance = TIM2;

 htim2.Init.Prescaler = 9;

 htim2.Init.CounterMode = TIM_COUNTERMODE_UP;

 htim2.Init.Period = 1500;

 htim2.Init.ClockDivision = TIM_CLOCKDIVISION_DIV1;

 htim2.Init.AutoReloadPreload = TIM_AUTORELOAD_PRELOAD_DISABLE;

 if (HAL_TIM_Base_Init(&htim2) != HAL_OK)

 {

  Error_Handler();

 }

 sClockSourceConfig.ClockSource = TIM_CLOCKSOURCE_INTERNAL;

 if (HAL_TIM_ConfigClockSource(&htim2, &sClockSourceConfig) != HAL_OK)

 {

  Error_Handler();

 }

 if (HAL_TIM_IC_Init(&htim2) != HAL_OK)

 {

  Error_Handler();

 }

 sSlaveConfig.SlaveMode = TIM_SLAVEMODE_RESET;

 sSlaveConfig.InputTrigger = TIM_TS_TI1FP1;

 sSlaveConfig.TriggerPolarity = TIM_INPUTCHANNELPOLARITY_FALLING;

 sSlaveConfig.TriggerPrescaler = TIM_ICPSC_DIV1;

 sSlaveConfig.TriggerFilter = 8;

 if (HAL_TIM_SlaveConfigSynchro(&htim2, &sSlaveConfig) != HAL_OK)

 {

  Error_Handler();

 }

 sConfigIC.ICPolarity = TIM_INPUTCHANNELPOLARITY_FALLING;

 sConfigIC.ICSelection = TIM_ICSELECTION_DIRECTTI;

 sConfigIC.ICPrescaler = TIM_ICPSC_DIV1;

 sConfigIC.ICFilter = 8;

 if (HAL_TIM_IC_ConfigChannel(&htim2, &sConfigIC, TIM_CHANNEL_1) != HAL_OK)

 {

  Error_Handler();

 }

 sConfigIC.ICPolarity = TIM_INPUTCHANNELPOLARITY_RISING;

 sConfigIC.ICSelection = TIM_ICSELECTION_INDIRECTTI;

 if (HAL_TIM_IC_ConfigChannel(&htim2, &sConfigIC, TIM_CHANNEL_2) != HAL_OK)

 {

  Error_Handler();

 }

 sMasterConfig.MasterOutputTrigger = TIM_TRGO_UPDATE;

 sMasterConfig.MasterSlaveMode = TIM_MASTERSLAVEMODE_DISABLE;

 if (HAL_TIMEx_MasterConfigSynchronization(&htim2, &sMasterConfig) != HAL_OK)

 {

  Error_Handler();

 }

 /* USER CODE BEGIN TIM2_Init 2 */

 /* USER CODE END TIM2_Init 2 */

}

/* TIM3 init function */

void MX_TIM3_Init(void)

{

 /* USER CODE BEGIN TIM3_Init 0 */

 /* USER CODE END TIM3_Init 0 */

 TIM_ClockConfigTypeDef sClockSourceConfig = {0};

 TIM_SlaveConfigTypeDef sSlaveConfig = {0};

 TIM_MasterConfigTypeDef sMasterConfig = {0};

 TIM_OC_InitTypeDef sConfigOC = {0};

 /* USER CODE BEGIN TIM3_Init 1 */

 /* USER CODE END TIM3_Init 1 */

 htim3.Instance = TIM3;

 htim3.Init.Prescaler = 9;

 htim3.Init.CounterMode = TIM_COUNTERMODE_UP;

 htim3.Init.Period = 1500;

 htim3.Init.ClockDivision = TIM_CLOCKDIVISION_DIV1;

 htim3.Init.AutoReloadPreload = TIM_AUTORELOAD_PRELOAD_DISABLE;

 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();

 }

 sSlaveConfig.SlaveMode = TIM_SLAVEMODE_RESET;

 sSlaveConfig.InputTrigger = TIM_TS_ITR1;

 if (HAL_TIM_SlaveConfigSynchro(&htim3, &sSlaveConfig) != 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 = 750;

 sConfigOC.OCPolarity = TIM_OCPOLARITY_LOW;

 sConfigOC.OCFastMode = TIM_OCFAST_DISABLE;

 if (HAL_TIM_PWM_ConfigChannel(&htim3, &sConfigOC, TIM_CHANNEL_1) != HAL_OK)

 {

  Error_Handler();

 }

 /* USER CODE BEGIN TIM3_Init 2 */

 /* USER CODE END TIM3_Init 2 */

 HAL_TIM_MspPostInit(&htim3);

}