Diff: main.cpp

Revision:

0:f610f2c606a8

Child:

1:843151144560

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp	Wed Feb 18 05:18:56 2015 +0000
@@ -0,0 +1,36 @@
+#include "mbed.h"
+#include "time.h"       
+
+DigitalOut myled(LED1);
+//serial connection via USB
+Serial pc(USBTX, USBRX); 
+AnalogIn pH_sensor(A0);
+
+int main()
+{
+    float voltage, pH, tempC, tempF;
+ 
+    while(1) {
+        double totalVal = 0.0;
+        double pH_sensor_read = 0.0;
+        int totalReadings = 0;
+        time_t start = time(NULL);
+        time_t seconds = 10;
+        time_t end = start + seconds;
+        while(time(NULL) < end){
+            pH_sensor_read = pH_sensor.read();
+            totalVal = totalVal + pH_sensor_read;
+            totalReadings++;
+            }
+            double avgSensor = totalVal/(double)totalReadings;
+        //hard coded calibration values taken at pH 4 solution to return voltage in mV
+        voltage = avgSensor*(800/.24);
+        //conversion to pH from sensor output voltage per LM61 data sheet
+        pH = (0.0209*voltage)-12.696;
+        //conversion to degrees C from sensor output voltage
+        tempC = (((voltage/1000) - 0.871481)/-0.0021504);
+        tempF = (tempC *9/5) + 32;
+        //print current pH and temp
+        pc.printf("pH = %5.2F & temp = %5.2F F\n\r", pH, tempF);            
+    }
+}
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