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DHT22.cpp
49 lines (44 loc) · 1.06 KB
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DHT22.cpp
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#include "DHT22.h"
DHT22::DHT22(PinName pin) {
_data_pin = pin;
}
int DHT22::getTemperature() {
return _temperature;
}
int DHT22::getHumidity() {
return _humidity;
}
bool DHT22::sample() {
DigitalInOut DHT22(_data_pin);
int dht22_dat [5];
DHT22.output();
DHT22.write(0);
wait_ms(18);
DHT22.write(1);
DHT22.input();
wait_us(40);
wait_us(80);
int i,j,result=0;
for (i=0; i<5; i++) {
result=0;
for (j=0; j<8; j++) {
while (DHT22);
while (!DHT22);
wait_us(50);
int p;
p=DHT22;
p=p <<(7-j);
result=result|p;
}
dht22_dat[i] = result;
}
int dht22_check_sum;
dht22_check_sum=dht22_dat[0]+dht22_dat[1]+dht22_dat[2]+dht22_dat[3];
dht22_check_sum= dht22_check_sum%256;
if (dht22_check_sum==dht22_dat[4]) {
_humidity=dht22_dat[0]*256+dht22_dat[1];
_temperature=dht22_dat[2]*256+dht22_dat[3];
return true;
}
return false;
}