Diff: main.cpp

Revision:

0:e6cfe26c00ef

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp	Thu Sep 24 12:30:45 2015 +0000
@@ -0,0 +1,99 @@
+#include "mbed.h"
+
+//Constants
+#define N 10
+
+//Function Prototype
+void doCaptureSamples();
+float updateAverage(float newSample, float buffer[]);
+
+//Global objects
+Serial pc(USBTX, USBRX);
+
+BusOut binaryOutput(D5, D6, D7);
+AnalogIn POT_ADC_In(A0);
+AnalogIn LDR_ADC_In(A1);
+DigitalOut strobe(D8);
+
+float xPOT[N]; //Aray of potentiometer samples
+float xLDR[N]; //Aray of LDR samples
+
+//These variables hold the next sample
+static float nextLDRSample, nextPOTSample;
+Ticker t;
+
+//Main function
+int main()
+{
+    //Set baud rate to 115200
+    pc.baud(115200);
+
+    //Print header
+    pc.printf("POT,LDR,avPOT, acLDR\n\n");
+
+    //Set up the ticker - 100Hz
+    t.attach(doCaptureSamples, 0.01);
+
+    while(1) {
+
+        //Sleep
+        sleep();
+
+        //Calculate averages
+        float fPOTAverage = updateAverage(nextPOTSample, xPOT);
+        float fLDRAverage = updateAverage(nextLDRSample, xLDR);
+        
+        //Write to terminal via Serial interface
+        pc.printf("%6.4f,%6.4f,%6.4f,%6.4f\n", xPOT[N/2], xLDR[N/2], fPOTAverage, fLDRAverage);
+
+        //Check the threshold
+        if (fLDRAverage > fPOTAverage) {
+            binaryOutput = 0;   //Binary 000
+        } else {
+            binaryOutput = 7;   //Binary 111
+        }
+
+    } //end while(1)
+} //end main
+
+//ISR for the ticker - simply there to perform sampling
+void doCaptureSamples()
+{
+    //Toggle digital out
+    strobe = !strobe;
+    
+    //READ ADC - store in static globals
+    //(static globals are shared with all functions in the same C or CPP file)
+    nextLDRSample = LDR_ADC_In;
+    nextPOTSample = POT_ADC_In;
+}
+
+/** Update and calculate the average. This has not been "hand optimised" yet 
+ *
+ * @param newSample The new sample to be added to the buffer
+ * @param buffer[] The array used to store N samples
+ * @returns
+ *   average of the samples in the array buffer
+ */
+float updateAverage(float newSample, float buffer[])
+{
+    //Local variable - remember to initialise!
+    float average = 0.0;
+    
+    //Move all samples to the right
+    for (unsigned int n=(N-1); n>0; n--) {
+        buffer[n] = buffer[n-1];    
+    }    
+    
+    //Insert new sample
+    buffer[0] = newSample;
+    
+    //Calculate average
+    for (unsigned int n=0; n<N; n++) {
+        average += buffer[n];    
+    }
+    average /= (float)N;
+    
+    //Return the result
+    return average;
+}
\ No newline at end of file