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NanoPi M1 Plus - DHT11 온도 습도 측정
출처 : DHT11 Humidity & Temperature Sensor Module | UUGear
C 언어
/*
* 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);
}
컴파일
# gcc -Wall -o dht11 dht11.c -lwiringPi -lpthread
실행
디버깅 모드 설정
# export WIRINGPI_DEBUG=TRUE
디버깅 모드 해지
# unset WIRINGPI_DEBUG
실행
# ./dht11 Raspberry Pi wiringPi DHT11 Temperature test program Data not good, skip Humidity = 22.0 % Temperature = 23.0 *C (73.4 *F) Humidity = 22.0 % Temperature = 23.0 *C (73.4 *F) Data not good, skip Data not good, skip Humidity = 22.0 % Temperature = 23.0 *C (73.4 *F)
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