Diff: DHT22.cpp

Revision:

1:8b95fd076a28

Parent:

0:7fd3ff04ae95

--- a/DHT22.cpp	Thu Oct 27 15:11:06 2011 +0000
+++ b/DHT22.cpp	Mon May 23 11:12:15 2016 +0000
@@ -1,8 +1,12 @@
 #include "DHT22.h"
 
+#define timeout 200
 
 DHT22::DHT22(PinName pin) {
     _data_pin = pin;
+    DigitalInOut dht(_data_pin);
+    dht.output();
+    dht.write(1);
 }
 
 int DHT22::getTemperature() {
@@ -14,36 +18,48 @@
 }
 
 bool DHT22::sample() {
-    DigitalInOut DHT22(_data_pin);
+    __disable_irq();    // Disable Interrupts
+    Timer t;
+    DigitalInOut dht(_data_pin);
     int dht22_dat [5];
-    DHT22.output();
-    DHT22.write(0);
-    wait_ms(18);
-    DHT22.write(1);
-    DHT22.input();
+    dht.output();
+    dht.write(0);
+    wait_ms(1);
+    dht.write(1);
+    dht.input();
     wait_us(40);
     wait_us(80);
     int i,j,result=0;
     for (i=0; i<5; i++) {
-        result=0;
+        result=0; 
         for (j=0; j<8; j++) {
-            while (DHT22);
-            while (!DHT22);
-            wait_us(50);
+            while(dht.read());
+            while(!dht.read());
+            t.reset();
+            t.start();
+            while(dht.read());
+            t.stop();
             int p;
-            p=DHT22;
+            if(t.read_us()>50)
+                p = 1;
+            else
+                p = 0;
             p=p <<(7-j);
             result=result|p;
         }
         dht22_dat[i] = result;
     }
+    dht.output();
+    dht.write(1);
     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];
+        __enable_irq();
         return true;
     }
+    __enable_irq();
     return false;
 }