I'm trying to use timer 2 in encoder mode (260000 points per revolution CH1 and CH2) and output an analog signal (on 12 bits) proportional to the position by passing only through the DMA. so far everything is working as expected but i'd like to use this encoder over a range of about 10° for an output of 0 to 3.3v. my first idea was to use a prescaler of 2, but the behavior is unstable when the prescaler is even. the solution would be to right shift the position of 1 to get the desired result, but this would use too much cpu capacity. would you have a solution for me?
Thank you for your reply.
Here is my timer configuration (timer 2 for encoder and timer 7 for DMA clock):
void MX_TIM2_Init(void)
{
/* USER CODE BEGIN TIM2_Init 0 */
/* USER CODE END TIM2_Init 0 */
TIM_Encoder_InitTypeDef sConfig = {0};
TIM_MasterConfigTypeDef sMasterConfig = {0};
/* USER CODE BEGIN TIM2_Init 1 */
/* USER CODE END TIM2_Init 1 */
htim2.Instance = TIM2;
htim2.Init.Prescaler = 0;
htim2.Init.CounterMode = TIM_COUNTERMODE_UP;
htim2.Init.Period = 260000;
htim2.Init.ClockDivision = TIM_CLOCKDIVISION_DIV1;
htim2.Init.AutoReloadPreload = TIM_AUTORELOAD_PRELOAD_ENABLE;
sConfig.EncoderMode = TIM_ENCODERMODE_TI12;
sConfig.IC1Polarity = TIM_ICPOLARITY_RISING;
sConfig.IC1Selection = TIM_ICSELECTION_DIRECTTI;
sConfig.IC1Prescaler = TIM_ICPSC_DIV1;
sConfig.IC1Filter = 10;
sConfig.IC2Polarity = TIM_ICPOLARITY_RISING;
sConfig.IC2Selection = TIM_ICSELECTION_DIRECTTI;
sConfig.IC2Prescaler = TIM_ICPSC_DIV1;
sConfig.IC2Filter = 10;
if (HAL_TIM_Encoder_Init(&htim2, &sConfig) != HAL_OK)
{
Error_Handler();
}
sMasterConfig.MasterOutputTrigger = TIM_TRGO_RESET;
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 */
}
/* TIM7 init function */
void MX_TIM7_Init(void)
{
/* USER CODE BEGIN TIM7_Init 0 */
/* USER CODE END TIM7_Init 0 */
TIM_MasterConfigTypeDef sMasterConfig = {0};
/* USER CODE BEGIN TIM7_Init 1 */
/* USER CODE END TIM7_Init 1 */
htim7.Instance = TIM7;
htim7.Init.Prescaler = 0;
htim7.Init.CounterMode = TIM_COUNTERMODE_UP;
htim7.Init.Period = 275;
htim7.Init.AutoReloadPreload = TIM_AUTORELOAD_PRELOAD_ENABLE;
if (HAL_TIM_Base_Init(&htim7) != HAL_OK)
{
Error_Handler();
}
sMasterConfig.MasterOutputTrigger = TIM_TRGO_UPDATE;
sMasterConfig.MasterSlaveMode = TIM_MASTERSLAVEMODE_DISABLE;
if (HAL_TIMEx_MasterConfigSynchronization(&htim7, &sMasterConfig) != HAL_OK)
{
Error_Handler();
}
/* USER CODE BEGIN TIM7_Init 2 */
/* USER CODE END TIM7_Init 2 */
}
Main.c
HAL_TIM_Encoder_Start(&htim2, TIM_CHANNEL_ALL);
HAL_DAC_Start(&hdac1, DAC_CHANNEL_1);
HAL_DAC_Start_DMA(&hdac1, DAC_CHANNEL_1, &TIM2->CNT, 1, DAC_ALIGN_12B_R);
HAL_TIM_Base_Start(&htim7);