main.cpp

00001 #include "mbed.h"
00002 
00003 //Constants
00004 #define N 10
00005 
00006 //Function Prototype
00007 void doCaptureSamples();
00008 float updateAverage(float newSample, float buffer[]);
00009 
00010 //Global objects
00011 Serial pc(USBTX, USBRX);
00012 
00013 BusOut binaryOutput(D5, D6, D7);
00014 AnalogIn POT_ADC_In(A0);
00015 AnalogIn LDR_ADC_In(A1);
00016 DigitalOut strobe(D8);
00017 
00018 float xPOT[N]; //Aray of potentiometer samples
00019 float xLDR[N]; //Aray of LDR samples
00020 
00021 //These variables hold the next sample
00022 static float nextLDRSample, nextPOTSample;
00023 
00024 //The location of the oldest sample
00025 static int indexOfOldest=(N-1);
00026 
00027 //These variables hold the average values
00028 float fPOTSum = 0.0;
00029 float fLDRSum = 0.0;
00030 
00031 //The ticker, used to sample data at a fixed rate
00032 Ticker t;
00033 
00034 //Main function
00035 int main()
00036 {
00037     //Set baud rate to 115200
00038     pc.baud(115200);
00039 
00040     //Print header
00041     pc.printf("POT,LDR,avPOT, acLDR\n\n");
00042 
00043     //Set up the ticker - 100Hz
00044     t.attach(doCaptureSamples, 0.01);
00045 
00046     while(1) {
00047 
00048         //Sleep
00049         sleep();
00050 
00051         //Update sums
00052         fPOTSum = fPOTSum + nextPOTSample - xPOT[indexOfOldest];
00053         fLDRSum = fLDRSum + nextLDRSample - xLDR[indexOfOldest];
00054 
00055         //Write new sample over the oldest
00056         xPOT[indexOfOldest] = nextPOTSample;
00057         xLDR[indexOfOldest] = nextLDRSample;
00058 
00059         //update positon of oldest sample
00060         indexOfOldest = (indexOfOldest==0) ? (N-1) : indexOfOldest-1;
00061 
00062         //Write to terminal via Serial interface
00063         int middle = (indexOfOldest - (N/2)) % N;
00064         pc.printf("%6.4f,%6.4f,%6.4f,%6.4f\n", xPOT[middle], xLDR[middle], fPOTSum/(float)N, fLDRSum/(float)N);
00065 
00066         //Check the threshold
00067         if (fLDRSum > fPOTSum) {
00068             binaryOutput = 0;   //Binary 000
00069         } else {
00070             binaryOutput = 7;   //Binary 111
00071         }
00072 
00073     } //end while(1)
00074 } //end main
00075 
00076 //ISR for the ticker - simply there to perform sampling
00077 void doCaptureSamples()
00078 {
00079     //Toggle digital out
00080     strobe = !strobe;
00081 
00082     //READ ADC - store in static globals
00083     //(static globals are shared with all functions in the same C or CPP file)
00084     nextLDRSample = LDR_ADC_In;
00085     nextPOTSample = POT_ADC_In;
00086 }
00087