/*
DHT 22 humidity and temperature sensor library

    Copyright (C) 2013  Fabio Angeletti - fabio.angeletti89@gmail.com

    See attached license.txt file

*/

/* includes --------------------------------------------------------- */
#include "dht22.h"

/* functions -------------------------------------------------------- */
/*
  configure DHT22_DATA as input
 */
void DHT22pinIn(void){
  GPIO_InitTypeDef GPIO_InitStructure;

  GPIO_InitStructure.Pin =  DHT22_DATA_PIN;
  GPIO_InitStructure.Mode = GPIO_MODE_INPUT;
  GPIO_InitStructure.Pull = GPIO_PULLUP;
  HAL_GPIO_Init(DHT22_GPIO, &GPIO_InitStructure);
}


/*
  configure DHT22_DATA as output
 */
void DHT22pinOut(void){
  GPIO_InitTypeDef GPIO_InitStructure;

  GPIO_InitStructure.Pin =  DHT22_DATA_PIN;
  GPIO_InitStructure.Mode = GPIO_MODE_OUTPUT_PP;
  GPIO_InitStructure.Pull = GPIO_PULLUP;
  HAL_GPIO_Init(DHT22_GPIO, &GPIO_InitStructure);
}


void DHT22_Init(void){
  //__HAL_RCC_GPIOE_CLK_ENABLE();
  DHT22pinOut();

  /* hold DHT22 in standby state */
  HAL_GPIO_WritePin(DHT22_GPIO, DHT22_DATA_PIN, GPIO_PIN_SET);
}


void DHT22_Read(TIM_HandleTypeDef timer){
  uint8_t dataIndex = 0;
  uint8_t counter = 7;
  uint8_t currByte = 0;
  uint8_t index = 0;
  uint32_t startTime = 0;

  /* reset data holder */
  for(index=0; index < 6; index++){
    DHT22data[index] = 0x00;
  }

  /* mcu sends start signal to sensor */
  DHT22pinOut();
  HAL_GPIO_WritePin(DHT22_GPIO, DHT22_DATA_PIN, GPIO_PIN_RESET);
  __HAL_TIM_SET_COUNTER(&timer, 0);

  /* wait for at least 20 mSecs */
  while(__HAL_TIM_GET_COUNTER(&timer) < 20000);

  /* switch to input and wait for sensor response */
  DHT22pinIn();
  while(HAL_GPIO_ReadPin(DHT22_GPIO, DHT22_DATA_PIN));

  /* DHT22 sends response signal */
  while(!HAL_GPIO_ReadPin(DHT22_GPIO, DHT22_DATA_PIN));
  while(HAL_GPIO_ReadPin(DHT22_GPIO, DHT22_DATA_PIN));

  /* DHT22 sends, finally, data */
  for (dataIndex=0; dataIndex<40; dataIndex++) {
    __HAL_TIM_SET_COUNTER(&timer, 0);
    while(!HAL_GPIO_ReadPin(DHT22_GPIO, DHT22_DATA_PIN));
    startTime = __HAL_TIM_GET_COUNTER(&timer);
    while(HAL_GPIO_ReadPin(DHT22_GPIO, DHT22_DATA_PIN));

    if ((__HAL_TIM_GET_COUNTER(&timer) - startTime) > 40){
      DHT22data[currByte] |= (1 << counter);
    }

    if (counter == 0) {   // next byte?
      counter = 7;        // restart at MSB
      currByte++;         // next byte!
    } else {
      counter--;
    }

  }
}


float DHT22getTemperature(void){
  float retVal;

  retVal = DHT22data[2] & 0x7F;
  retVal *= 256;
  retVal += DHT22data[3];
  retVal /= 10;

  if (DHT22data[2] & 0x80)
    retVal *= -1;

  return retVal;
}


float DHT22getHumidity(void){
  float retVal;

  retVal = DHT22data[0];
  retVal *= 256;
  retVal += DHT22data[1];
  retVal /= 10;

  return retVal;
}


float convertCtoF(float cTemperature){
  return cTemperature * 9 / 5 + 32;
}