AnsweredAssumed Answered

One-Wire protocol with Input capture

Question asked by AntonioB on Sep 23, 2016
Latest reply on Sep 23, 2016 by FTITI.Walid
Hi to all i have this problem, i have a STM32L152RE with a temperature Sensor,
this sensor use 1-wire protocol,the data is codifing with pulse width,
lather the mcu start the connection the sensor give the 40 bit,
i have 0 if the pulse width is 28 usec, i have 1 if the pulse is 70 usec.

I use cube_mx for configure the board, i use the time3, channel 2 with interrupt,
this is the my configuration
/* TIM3 init function */
static void MX_TIM3_Init(void)
{

  TIM_ClockConfigTypeDef sClockSourceConfig;
  TIM_MasterConfigTypeDef sMasterConfig;
  TIM_IC_InitTypeDef sConfigIC;

  htim3.Instance = TIM3;
  htim3.Init.Prescaler = 32000;   //1MHz
  htim3.Init.CounterMode = TIM_COUNTERMODE_UP;
  htim3.Init.Period = 65535;
  htim3.Init.ClockDivision = TIM_CLOCKDIVISION_DIV1;
  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_IC_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();
  }

  sConfigIC.ICPolarity = TIM_INPUTCHANNELPOLARITY_RISING;
  sConfigIC.ICSelection = TIM_ICSELECTION_DIRECTTI;
  sConfigIC.ICPrescaler = TIM_ICPSC_DIV1;
  sConfigIC.ICFilter = 15;   // input filter
  if (HAL_TIM_IC_ConfigChannel(&htim3, &sConfigIC, TIM_CHANNEL_2) != HAL_OK)
  {
    Error_Handler();
  }






now all work well, but where should I set the width codifing?:

void HAL_TIM_IC_CaptureCallback(TIM_HandleTypeDef *htim)
{
  int i=0;
  uint32_t input_capture;
    if (htim->Instance==TIM3)
        {
                  
            input_capture=__HAL_TIM_GetCompare(&htim3, TIM_CHANNEL_2);    //READ TIM3 channel 2

                 
                 printf ( " Value: %u \n \r " , input_capture); // debug
...                 
                 }



can you help me?


best regards
antonio

Outcomes