DHT22.c

//==============================================================================
//
//  main.h
//
//
//==============================================================================
//  FILE INFORMATION
//==============================================================================
//
//  Source:
//
//  Project:    Humidity and temperature monitoring
//
//  Author:     M.Shahzad
//
//  Date:       20/03/2023
//
//  Revision:   1.0
//
//==============================================================================
//  FILE DESCRIPTION
//==============================================================================
//
//! \file
//! This module takes care of the
//
//==============================================================================
//  REVISION HISTORY
//==============================================================================
//  Revision: 1.0
//
//

//==============================================================================
//  INCLUDES
//==============================================================================

#include "DHT22.h"

//==============================================================================
//
//   void floattostr_(float x, unsigned char *str, char precision)
//
//   Author:   M. Shahzad
//   Date:     06/08/2021
//
//! This function used to convert float data to string
//
//==============================================================================

void floattostr_(float x, unsigned char *str, char precision)
{
	// convert float to string data
	int ie, i, k, ndig;
	double y;
	ndig = (precision <= 0) ? 7 : (precision > 22 ? 23 : precision + 1);
	ie = 0;
	/* if x negative, write minus and reverse */
	if (x < 0)
	{
		*str++ = '-';
		x = -x;
	}
	/* put x in range 1 <= x < 10 */
	if (x > 0.0)
		while (x < 1.0)
		{
			x *= 10.0; // a la place de =*
			ie--;
		}
	while (x >= 10.0)
	{
		x = x / 10.0;
		ie++;
	}
	ndig += ie; // a la place de =+
	// round. x is between 1 and 10 and ndig will be printed to
	//  right of decimal point so rounding is ...
	for (y = i = 1; i < ndig; i++)
		y = y / 10.;
	x += y / 2.;
	if (x >= 10.0)
	{
		x = 1.0;
		ie++;
	}

	if (ie < 0)
	{
		*str++ = '0';
		*str++ = '.';
		if (ndig < 0)
			ie = ie - ndig;
		for (i = -1; i > ie; i--)
			*str++ = '0';
	}
	for (i = 0; i < ndig; i++)
	{
		k = x;
		*str++ = k + '0';
		if (i == ie)
			*str++ = '.';
		x -= (y = k);
		x *= 10.0;
	}
	*str = '\0';
}

//==============================================================================
//
//   char dht22_get_byte(char s_number)
//
//   Author:   M. Shahzad
//   Date:     06/08/2021
//
//! Get the values of DHT11
//
//==============================================================================

char dht22_get_byte(char s_number)
{
	char dht22_data, count_for, delaycnt = 0;

	for (count_for = 0; count_for < 8; count_for++)
	{
		while (!dht22_S1_pin)
		{
			Delay_us(1);
			delaycnt++;
			if (delaycnt > 250)
				break;
		}
		delay_us(30);
		delaycnt = 0;

		if (dht22_S1_pin == 0)
			dht22_data &= ~(1 << (7 - count_for));
		else
		{
			dht22_data |= (1 << (7 - count_for));
			while (dht22_S1_pin)
			{
				Delay_us(1);
				delaycnt++;
				if (delaycnt > 250)
					break;
			}
		}
	}
	return dht22_data;
}

//==============================================================================
//
//   char dht22_S1_function(char value)
//
//   Author:   M. Shahzad
//   Date:     06/08/2021
//
//! This function reads temperatue and humidity values from the sensors
//
//==============================================================================

char dht22_S1_function(char value)
{
	char res_ = 0;
	dht22_S1_pin_direction = 0;
	dht22_S1_pin = 0;
	delay_ms(18);

	dht22_S1_pin = 1;
	delay_us(30);
	dht22_S1_pin_direction = 1; // configura entrada pin del sensor

	delay_us(40);
	if (dht22_S1_pin == 0)
	{
		delay_us(80);
		if (dht22_S1_pin == 1)
			res_ = 1;
		delay_us(40);
	}
	if (res_ == dht22_noresponse)
		return (res_);

	res_ = 0; // inicializa cero para procesar lectura

	dht22_S1_object.hum1_ = dht22_get_byte(1);
	dht22_S1_object.hum2_ = dht22_get_byte(1);
	dht22_S1_object.temp1_ = dht22_get_byte(1);

	dht22_S1_object.temp2_ = dht22_get_byte(1);
	dht22_S1_object.checksum_ = dht22_get_byte(1);

	if (dht22_S1_object.checksum_ == ((dht22_S1_object.hum1_ + dht22_S1_object.hum2_ + dht22_S1_object.temp1_ + dht22_S1_object.temp2_) & 0XFF))
	{
		// Calcula Temperatura
		dht22_S1_object.Temp_ = dht22_S1_object.temp1_;
		dht22_S1_object.Temp_ = (dht22_S1_object.Temp_ << 8) | dht22_S1_object.Temp2_;

		if (dht22_S1_object.Temp_ > 0X8000)
		{
			dht22_S1_object.Temp_ = dht22_S1_object.Temp_ & 0X7FFF;
		}
		dht22_S1_object.temperature_ = dht22_S1_object.Temp_ / 10.0;
		// calcula Humedad
		dht22_S1_object.hume_ = dht22_S1_object.hum1_;
		dht22_S1_object.hume_ = (dht22_S1_object.hume_ << 8) | dht22_S1_object.hum2_;
		dht22_S1_object.humedad_ = dht22_S1_object.hume_ / 10.0;
		res_ = 1;
	}
	if (res_ = dht22_noresponse)
		return (dht22_errorcheck_sum);
	else
		return (dht22_ok);
}