라즈베리 파이 - dht11 온도/습도센서

결국은 비표준 통신이라.

GPIO로 쌩 고생을 시켜야하나...

/*  *  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); } [링크 : http://www.uugear.com/portfolio/dht11-humidity-temperature-sensor-module/]

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2015.07.14

입김불고 얼음대고 온도 변화주기

$ gcc dht11.c -lwiringPi $ sudo ./a.out Raspberry Pi wiringPi DHT11 Temperature test program Humidity = 63.0 % Temperature = 26.0 *C (78.8 *F) Data not good, skip ... Humidity = 85.0 % Temperature = 30.0 *C (86.0 *F) ... Humidity = 80.0 % Temperature = 25.0 *C (77.0 *F) Humidity = 73.0 % Temperature = 24.0 *C (75.2 *F) Humidity = 73.0 % Temperature = 23.0 *C (73.4 *F) Humidity = 71.0 % Temperature = 22.0 *C (71.6 *F)

소스상 GPIO 4 / 7번 핀을 사용하므로 적절하게 연결!

전체구성은 대충 이런 느낌적인 느낌으로