Etienne Charbonnier / Mbed OS plant_monitoring

Plant Monitoring CS

Dependencies:   HTS221

DHT22.cpp@59:169324c8e604, 2020-03-25 (annotated)

Committer:
titi9211
Date:
Wed Mar 25 15:46:56 2020 +0000
Revision:
59:169324c8e604
Plant Monitoring Program

Who changed what in which revision?

UserRevisionLine numberNew contents of line
titi9211 59:169324c8e604 1 #include "DHT22.h"
titi9211 59:169324c8e604 2
titi9211 59:169324c8e604 3
titi9211 59:169324c8e604 4 DHT22::DHT22(PinName pin) {
titi9211 59:169324c8e604 5 _data_pin = pin;
titi9211 59:169324c8e604 6 }
titi9211 59:169324c8e604 7
titi9211 59:169324c8e604 8 int DHT22::getTemperature() {
titi9211 59:169324c8e604 9 return _temperature;
titi9211 59:169324c8e604 10 }
titi9211 59:169324c8e604 11
titi9211 59:169324c8e604 12 int DHT22::getHumidity() {
titi9211 59:169324c8e604 13 return _humidity;
titi9211 59:169324c8e604 14 }
titi9211 59:169324c8e604 15
titi9211 59:169324c8e604 16 bool DHT22::sample() {
titi9211 59:169324c8e604 17 DigitalInOut DHT22(_data_pin);
titi9211 59:169324c8e604 18 int dht22_dat [5];
titi9211 59:169324c8e604 19 DHT22.output();
titi9211 59:169324c8e604 20 DHT22.write(0);
titi9211 59:169324c8e604 21 wait_ms(18);
titi9211 59:169324c8e604 22 DHT22.write(1);
titi9211 59:169324c8e604 23 DHT22.input();
titi9211 59:169324c8e604 24 wait_us(40);
titi9211 59:169324c8e604 25 wait_us(80);
titi9211 59:169324c8e604 26 int i,j,result=0;
titi9211 59:169324c8e604 27 for (i=0; i<5; i++) {
titi9211 59:169324c8e604 28 result=0;
titi9211 59:169324c8e604 29 for (j=0; j<8; j++) {
titi9211 59:169324c8e604 30 while (DHT22);
titi9211 59:169324c8e604 31 while (!DHT22);
titi9211 59:169324c8e604 32 wait_us(50);
titi9211 59:169324c8e604 33 int p;
titi9211 59:169324c8e604 34 p=DHT22;
titi9211 59:169324c8e604 35 p=p <<(7-j);
titi9211 59:169324c8e604 36 result=result|p;
titi9211 59:169324c8e604 37 }
titi9211 59:169324c8e604 38 dht22_dat[i] = result;
titi9211 59:169324c8e604 39 }
titi9211 59:169324c8e604 40 int dht22_check_sum;
titi9211 59:169324c8e604 41 dht22_check_sum=dht22_dat[0]+dht22_dat[1]+dht22_dat[2]+dht22_dat[3];
titi9211 59:169324c8e604 42 dht22_check_sum= dht22_check_sum%256;
titi9211 59:169324c8e604 43 if (dht22_check_sum==dht22_dat[4]) {
titi9211 59:169324c8e604 44 _humidity=dht22_dat[0]*256+dht22_dat[1];
titi9211 59:169324c8e604 45 _temperature=dht22_dat[2]*256+dht22_dat[3];
titi9211 59:169324c8e604 46 return true;
titi9211 59:169324c8e604 47 }
titi9211 59:169324c8e604 48 return false;
titi9211 59:169324c8e604 49 }