University of Plymouth - Stages 1, 2 and 3 / Mbed OS Task434Solution

Task 4.3.4 Solution

Fork of Task434Solution by Nicholas Outram

main.cpp@0:6a8980b23272, 2015-09-24 (annotated)

Committer:
noutram
Date:
Thu Sep 24 12:30:37 2015 +0000
Revision:
0:6a8980b23272
Initial version 24-09-2015

Who changed what in which revision?

UserRevisionLine numberNew contents of line
noutram 0:6a8980b23272 1 #include "mbed.h"
noutram 0:6a8980b23272 2
noutram 0:6a8980b23272 3 //Constants
noutram 0:6a8980b23272 4 #define N 10
noutram 0:6a8980b23272 5
noutram 0:6a8980b23272 6 //Function Prototype
noutram 0:6a8980b23272 7 float updateAverage(float newSample, float buffer[]);
noutram 0:6a8980b23272 8
noutram 0:6a8980b23272 9 //Global objects
noutram 0:6a8980b23272 10 Serial pc(USBTX, USBRX);
noutram 0:6a8980b23272 11
noutram 0:6a8980b23272 12 BusOut binaryOutput(D5, D6, D7);
noutram 0:6a8980b23272 13 AnalogIn POT_ADC_In(A0);
noutram 0:6a8980b23272 14 AnalogIn LDR_ADC_In(A1);
noutram 0:6a8980b23272 15
noutram 0:6a8980b23272 16 float xPOT[N]; //Aray of potentiometer samples
noutram 0:6a8980b23272 17 float xLDR[N]; //Aray of LDR samples
noutram 0:6a8980b23272 18
noutram 0:6a8980b23272 19 //Main function
noutram 0:6a8980b23272 20 int main()
noutram 0:6a8980b23272 21 {
noutram 0:6a8980b23272 22
noutram 0:6a8980b23272 23 //Set baud rate to 115200
noutram 0:6a8980b23272 24 pc.baud(115200);
noutram 0:6a8980b23272 25
noutram 0:6a8980b23272 26 //Print header
noutram 0:6a8980b23272 27 pc.printf("POT,LDR,avPOT, acLDR\n\n");
noutram 0:6a8980b23272 28
noutram 0:6a8980b23272 29 while(1) {
noutram 0:6a8980b23272 30
noutram 0:6a8980b23272 31 //Calculate averages
noutram 0:6a8980b23272 32 float fPOTAverage = updateAverage(POT_ADC_In, xPOT);
noutram 0:6a8980b23272 33 float fLDRAverage = updateAverage(LDR_ADC_In, xLDR);
noutram 0:6a8980b23272 34
noutram 0:6a8980b23272 35 //Write to terminal via Serial interface
noutram 0:6a8980b23272 36 pc.printf("%6.4f,%6.4f,%6.4f,%6.4f\n", xPOT[N/2], xLDR[N/2], fPOTAverage, fLDRAverage);
noutram 0:6a8980b23272 37
noutram 0:6a8980b23272 38 //Check the threshold
noutram 0:6a8980b23272 39 if (fLDRAverage > fPOTAverage) {
noutram 0:6a8980b23272 40 binaryOutput = 0; //Binary 000
noutram 0:6a8980b23272 41 } else {
noutram 0:6a8980b23272 42 binaryOutput = 7; //Binary 111
noutram 0:6a8980b23272 43 }
noutram 0:6a8980b23272 44
noutram 0:6a8980b23272 45 //Wait 1/100th second
noutram 0:6a8980b23272 46 wait(0.01);
noutram 0:6a8980b23272 47
noutram 0:6a8980b23272 48
noutram 0:6a8980b23272 49 } //end while(1)
noutram 0:6a8980b23272 50 } //end main
noutram 0:6a8980b23272 51
noutram 0:6a8980b23272 52
noutram 0:6a8980b23272 53 /** Update and calculate the average. This has not been "hand optimised" yet
noutram 0:6a8980b23272 54 *
noutram 0:6a8980b23272 55 * @param newSample The new sample to be added to the buffer
noutram 0:6a8980b23272 56 * @param buffer[] The array used to store N samples
noutram 0:6a8980b23272 57 * @returns
noutram 0:6a8980b23272 58 * average of the samples in the array buffer
noutram 0:6a8980b23272 59 */
noutram 0:6a8980b23272 60 float updateAverage(float newSample, float buffer[])
noutram 0:6a8980b23272 61 {
noutram 0:6a8980b23272 62 //Local variable - remember to initialise!
noutram 0:6a8980b23272 63 float average = 0.0;
noutram 0:6a8980b23272 64
noutram 0:6a8980b23272 65 //Move all samples to the right
noutram 0:6a8980b23272 66 for (unsigned int n=(N-1); n>0; n--) {
noutram 0:6a8980b23272 67 buffer[n] = buffer[n-1];
noutram 0:6a8980b23272 68 }
noutram 0:6a8980b23272 69
noutram 0:6a8980b23272 70 //Insert new sample
noutram 0:6a8980b23272 71 buffer[0] = newSample;
noutram 0:6a8980b23272 72
noutram 0:6a8980b23272 73 //Calculate average
noutram 0:6a8980b23272 74 for (unsigned int n=0; n<N; n++) {
noutram 0:6a8980b23272 75 average += buffer[n];
noutram 0:6a8980b23272 76 }
noutram 0:6a8980b23272 77 average /= (float)N;
noutram 0:6a8980b23272 78
noutram 0:6a8980b23272 79 //Return the result
noutram 0:6a8980b23272 80 return average;
noutram 0:6a8980b23272 81 }