Revision 5:76a9332af64c, committed 2015-01-06

Comitter:

kaliczp

Date:

Tue Jan 06 00:54:41 2015 +0000

Parent:

4:62b680fac6ed

Child:

6:8027edc2b69f

Child:

7:5b0793a2b391

Commit message:

Send the measured data bits of DHT11 through UART!

Changed in this revision

--- a/main.cpp	Tue Jan 06 00:48:44 2015 +0000
+++ b/main.cpp	Tue Jan 06 00:54:41 2015 +0000
@@ -5,6 +5,9 @@
 DigitalInOut data_pin(A0); // Activate digital in
 Serial pc(SERIAL_TX, SERIAL_RX); // Initialize UART connection
 // Use a terminal program (eg. TeraTerm).
+Timer tmr; //initialize timer
+char adat[40]; // Array for data
+int i;
 
 // Function to initialize DHT11
 void dht_read(void) {
@@ -15,14 +18,40 @@
     // After high and release the pin switch input mode
     data_pin = 1;
     data_pin.input();
+    // Wait until the end of 80 us low
+    while(!data_pin.read()) {}
+    // Wait until end of 80 us high
+    while(data_pin.read()) {}
+    // 40 bit, 40 read out cycle
+    for(i=0; i<40; i++) {
+        tmr.stop(); // Stop timer if runs
+        tmr.reset();  // Reset timer
+        // Wait until pin
+        while(!data_pin.read()) {}          
+        tmr.start();            
+        while(data_pin.read()) {}
+        // If DHT11 HIGH longer than 40 micro seconds (hopefully 70 us)
+        if(tmr.read_us() > 40) {
+            // bit is 1
+            adat[i] = 1;
+        }
+    }
 }
 
 int main() {
     pc.printf("Read the DHT11 temperature and humidity sensor!\n"); //Welcome message
     while(1) {
         if (mybutton == 0) { // Button is pressed
+            // Reset character array
+            for(i=0; i < 40; i++){
+                adat[i] = 0;
+            }
             myled = 1; // LED is ON
             dht_read(); // Call the function
+            // Send result through UART result
+            for(i=0; i < 40; i++){
+                pc.printf("%d",adat[i]);
+            }
             wait_ms(200); // Wait 0.2 sec till continue.
         } else {
             myled = 0; // LED is OFF