I used this code to read dht22 with atmega but it reads wrong valuea, could you tell me why
Code:
ATmega16_DHT11_Project_File.c
*
* http://www.electronicwings.com
*/
#include <avr/io.h>
#include <stdlib.h>
#include <stdio.h>
#include "LCD16x2_4bit.h"
#define DHT11_PIN 6
uint8_t c=0,I_RH,D_RH,I_Temp,D_Temp,CheckSum;
void Request() /* Microcontroller send start pulse/request */
{
DDRD |= (1<<DHT11_PIN);
PORTD &= ~(1<<DHT11_PIN); /* set to low pin */
_delay_ms(20); /* wait for 20ms */
PORTD |= (1<<DHT11_PIN); /* set to high pin */
}
void Response() /* receive response from DHT11 */
{
DDRD &= ~(1<<DHT11_PIN);
while(PIND & (1<<DHT11_PIN));
while((PIND & (1<<DHT11_PIN))==0);
while(PIND & (1<<DHT11_PIN));
}
uint8_t Receive_data() /* receive data */
{
for (int q=0; q<8; q++)
{
while((PIND & (1<<DHT11_PIN)) == 0); /* check received bit 0 or 1 */
_delay_us(30);
if(PIND & (1<<DHT11_PIN))/* if high pulse is greater than 30ms */
c = (c<<1)|(0x01); /* then its logic HIGH */
else /* otherwise its logic LOW */
c = (c<<1);
while(PIND & (1<<DHT11_PIN));
}
return c;
}
int main(void)
{
char data[5];
lcdinit(); /* Initialize LCD */
lcd_clear(); /* Clear LCD */
lcd_gotoxy(0,0); /* Enter column and row position */
lcd_print("Humidity =");
lcd_gotoxy(0,1);
lcd_print("Temp = ");
while(1)
{
Request(); /* send start pulse */
Response(); /* receive response */
I_RH=Receive_data(); /* store first eight bit in I_RH */
D_RH=Receive_data(); /* store next eight bit in D_RH */
I_Temp=Receive_data(); /* store next eight bit in I_Temp */
D_Temp=Receive_data(); /* store next eight bit in D_Temp */
CheckSum=Receive_data();/* store next eight bit in CheckSum */
if ((I_RH + D_RH + I_Temp + D_Temp) != CheckSum)
{
lcd_gotoxy(0,0);
lcd_print("Error");
}
else
{
itoa(I_RH,data,10);
lcd_gotoxy(11,0);
lcd_print(data);
lcd_print(".");
itoa(D_RH,data,10);
lcd_print(data);
lcd_print("%");
itoa(I_Temp,data,10);
lcd_gotoxy(6,1);
lcd_print(data);
lcd_print(".");
itoa(D_Temp,data,10);
lcd_print(data);
lcddata(0xDF);
lcd_print("C ");
itoa(CheckSum,data,10);
lcd_print(data);
lcd_print(" ");
}
_delay_ms(10);
}
}
