Not a member of Pastebin yet?
Sign Up,
it unlocks many cool features!
- /*
- * dht11.c:
- * Simple test program to test the wiringPi functions
- * DHT11 test
- */
- #include <wiringPi.h>
- #include <stdio.h>
- #include <stdlib.h>
- #include <stdint.h>
- #define MAXTIMINGS 85
- #define DHTPIN 7
- int dht11_dat[5] = { 0, 0, 0, 0, 0 };
- void read_dht11_dat()
- {
- uint8_t laststate = HIGH;
- uint8_t counter = 0;
- uint8_t j = 0, i;
- float f; /* fahrenheit */
- dht11_dat[0] = dht11_dat[1] = dht11_dat[2] = dht11_dat[3] = dht11_dat[4] = 0;
- /* pull pin down for 18 milliseconds */
- pinMode( DHTPIN, OUTPUT );
- digitalWrite( DHTPIN, LOW );
- delay( 18 );
- /* then pull it up for 40 microseconds */
- digitalWrite( DHTPIN, HIGH );
- delayMicroseconds( 40 );
- /* prepare to read the pin */
- pinMode( DHTPIN, INPUT );
- /* detect change and read data */
- for ( i = 0; i < MAXTIMINGS; i++ )
- {
- counter = 0;
- while ( digitalRead( DHTPIN ) == laststate )
- {
- counter++;
- delayMicroseconds( 1 );
- if ( counter == 255 )
- {
- break;
- }
- }
- laststate = digitalRead( DHTPIN );
- if ( counter == 255 )
- break;
- /* ignore first 3 transitions */
- if ( (i >= 4) && (i % 2 == 0) )
- {
- /* shove each bit into the storage bytes */
- dht11_dat[j / 8] <<= 1;
- if ( counter > 16 )
- dht11_dat[j / 8] |= 1;
- j++;
- }
- }
- /*
- * check we read 40 bits (8bit x 5 ) + verify checksum in the last byte
- * print it out if data is good
- */
- if ( (j >= 40) &&
- (dht11_dat[4] == ( (dht11_dat[0] + dht11_dat[1] + dht11_dat[2] + dht11_dat[3]) & 0xFF) ) )
- {
- f = dht11_dat[2] * 9. / 5. + 32;
- printf( "Humidity = %d.%d %% Temperature = %d.%d *C (%.1f *F)\n",
- dht11_dat[0], dht11_dat[1], dht11_dat[2], dht11_dat[3], f );
- }else {
- printf( "Data not good, skip\n" );
- }
- }
- int main( void )
- {
- printf( "Raspberry Pi wiringPi DHT11 Temperature test program\n" );
- if ( wiringPiSetup() == -1 )
- exit( 1 );
- while ( 1 )
- {
- read_dht11_dat();
- delay( 1000 ); /* wait 1sec to refresh */
- }
- return(0);
- }
Add Comment
Please, Sign In to add comment