main.cpp

00001 #include "mbed.h"
00002 
00003 //Constants
00004 #define N 10
00005 
00006 //Function Prototype
00007 float updateAverage(float newSample, float buffer[]);
00008 
00009 //Global objects
00010 Serial pc(USBTX, USBRX);
00011 
00012 BusOut binaryOutput(D5, D6, D7);
00013 AnalogIn POT_ADC_In(A0);
00014 AnalogIn LDR_ADC_In(A1);
00015 
00016 float xPOT[N]; //Aray of potentiometer samples
00017 float xLDR[N]; //Aray of LDR samples
00018 
00019 //Main function
00020 int main()
00021 {
00022 
00023     //Set baud rate to 115200
00024     pc.baud(115200);
00025 
00026     //Print header
00027     pc.printf("POT,LDR,avPOT, acLDR\n\n");
00028 
00029     while(1) {
00030 
00031         //Calculate averages
00032         float fPOTAverage = updateAverage(POT_ADC_In, xPOT);
00033         float fLDRAverage = updateAverage(LDR_ADC_In, xLDR);
00034         
00035         //Write to terminal via Serial interface
00036         pc.printf("%6.4f,%6.4f,%6.4f,%6.4f\n", xPOT[N/2], xLDR[N/2], fPOTAverage, fLDRAverage);
00037 
00038         //Check the threshold
00039         if (fLDRAverage > fPOTAverage) {
00040             binaryOutput = 0;   //Binary 000
00041         } else {
00042             binaryOutput = 7;   //Binary 111
00043         }
00044 
00045         //Wait 1/100th second
00046         wait(0.01);
00047 
00048 
00049     } //end while(1)
00050 } //end main
00051 
00052 
00053 /** Update and calculate the average. This has not been "hand optimised" yet 
00054  *
00055  * @param newSample The new sample to be added to the buffer
00056  * @param buffer[] The array used to store N samples
00057  * @returns
00058  *   average of the samples in the array buffer
00059  */
00060 float updateAverage(float newSample, float buffer[])
00061 {
00062     //Local variable - remember to initialise!
00063     float average = 0.0;
00064     
00065     //Move all samples to the right
00066     for (unsigned int n=(N-1); n>0; n--) {
00067         buffer[n] = buffer[n-1];    
00068     }    
00069     
00070     //Insert new sample
00071     buffer[0] = newSample;
00072     
00073     //Calculate average
00074     for (unsigned int n=0; n<N; n++) {
00075         average += buffer[n];    
00076     }
00077     average /= (float)N;
00078     
00079     //Return the result
00080     return average;
00081 }