Diff: DHT22.cpp

Revision:

0:7fd3ff04ae95

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/DHT22.cpp	Thu Oct 27 15:11:06 2011 +0000
@@ -0,0 +1,49 @@
+#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;
+}