File content as of revision 0:f0824fc8b273:

#include "suli2.h"
#include "grove_temp_hum.h"



//local functions
static bool _read(IO_T *io);
static float grove_temp_hum_convertCtoF(float c);



//local variables
static uint8_t _type, _count;
static bool firstreading;
static unsigned long _lastreadtime;
static uint8_t data[6];



void grove_temp_hum_init(IO_T *io, int pin)
{
    suli_pin_init(io, pin, SULI_INPUT);
}

bool grove_temp_hum_write_setup(IO_T *io, uint8_t type, uint8_t count)
{
    _type = type;
    _count = count;
    firstreading = true;
    return true;
}
static bool _read(IO_T *io)
{
  uint8_t laststate = SULI_HIGH;
  uint8_t counter = 0;
  uint8_t j = 0, i;
  unsigned long currenttime;

  // pull the pin high and wait 250 milliseconds
  //digitalWrite(_pin, SULI_HIGH);
  suli_pin_write(io, SULI_HIGH);
  suli_delay_ms(250);

  currenttime = suli_millis();
  if (currenttime < _lastreadtime) {
    // ie there was a rollover
    _lastreadtime = 0;
  }
  if (!firstreading && ((currenttime - _lastreadtime) < 2000)) {
    return true; // return last correct measurement
    //delay(2000 - (currenttime - _lastreadtime));
  }
  firstreading = false;

  _lastreadtime = suli_millis();

  data[0] = data[1] = data[2] = data[3] = data[4] = 0;
  
  // now pull it low for ~20 milliseconds
  //pinMode(_pin, OUTPUT);
  suli_pin_dir(io, SULI_OUTPUT)
  //digitalWrite(_pin, LOW);
  suli_pin_write(io, SULI_LOW);
  suli_delay_ms(20);
  //cli();
  //digitalWrite(_pin, SULI_HIGH);
  suli_pin_write(io, SULI_HIGH);
  //delayMicroseconds(40);
  suli_delay_us(40);
  //pinMode(_pin, INPUT);
  suli_pin_dir(io, SULI_INPUT)
  // read in timings
  for ( i=0; i< MAXTIMINGS; i++) {
    counter = 0;
    //while (digitalRead(_pin) == laststate) {
    while (suli_pin_read(io) == laststate) {
      counter++;
      //delayMicroseconds(1);
      suli_delay_us(1);
      if (counter == 255) {
        break;
      }
    }
    //laststate = digitalRead(&_pin);
    laststate = suli_pin_read(io);

    if (counter == 255) break;

    // ignore first 3 transitions
    if ((i >= 4) && (i%2 == 0)) {
      // shove each bit into the storage bytes
      data[j/8] <<= 1;
      if (counter > _count)//
        data[j/8] |= 1;
      j++;
    }

  }

  // check we read 40 bits and that the checksum matches
  if ((j >= 40) && 
      (data[4] == ((data[0] + data[1] + data[2] + data[3]) & 0xFF)) ) {
    return true;
  }
  

  return false;

}

static float grove_temp_hum_convertCtoF(float c) {
    return c * 9 / 5 + 32;
}

//boolean S == Scale.  True == Farenheit; False == Celcius
bool grove_temp_hum_readtemperature(IO_T *io, bool S, float *temperature)
{
  float f;

  if (_read(io)) {
    switch (_type) {
    case DHT11:
      f = data[2];
      if(S)
        f = grove_temp_hum_convertCtoF(f);
        *temperature = f;
      return true;
    case DHT22:
    case DHT21:
      f = data[2] & 0x7F;
      f *= 256;
      f += data[3];
      f /= 10;
      if (data[2] & 0x80)
    f *= -1;
      if(S)
    f = grove_temp_hum_convertCtoF(f);
      *temperature = f;
      return true;
    }
  }
  //Serial.print("Read fail");
  return false;
}

bool grove_temp_hum_readhumidity(IO_T *io,  float *humidity)
{
  float f;
  if (_read(io)) {
    switch (_type) {
    case DHT11:
      f = data[0];
      *humidity = f;
      return true;
    case DHT22:
    case DHT21:
      f = data[0];
      f *= 256;
      f += data[1];
      f /= 10;
       *humidity = f;
      return true;
    }
  }
  //Serial.print("Read fail");
  return false;
}