main.cpp

00001 #include "mbed.h"
00002 
00003 #define NUM_SAMPLES 500000 // size of sample series
00004 #define SAMPLE_BLOCKS 5
00005 
00006 Timer t;
00007 
00008 Serial pc(USBTX,USBRX);
00009 
00010 AnalogIn ain(p17);
00011 
00012 // initialise error counters
00013 int num_4;
00014 int num_8;
00015 int num_16;
00016 int num_32;
00017 int num_64;
00018 int num_128;
00019 int num_256;
00020 int num_512;
00021 int num_1024;
00022 int num_spike;
00023 
00024 int main() {
00025 
00026     int num_samples = 0;
00027 
00028     num_4 = 0;
00029     num_8 = 0;
00030     num_16 = 0;
00031     num_32 = 0;
00032     num_64 = 0;
00033     num_128 = 0;
00034     num_256 = 0;
00035     num_512 = 0;
00036     num_1024 = 0;
00037     num_spike = 0;
00038 
00039 
00040 // Take the average over 500,000 samples
00041 // This is because the bias to 1.65v has a tolerance
00042     float AVERAGE = 0.5;
00043 
00044     pc.printf("Taking an average over %d samples\n",NUM_SAMPLES);
00045     while (num_samples < NUM_SAMPLES) {
00046         float r = ain.read();
00047 
00048         if ((r > 0.45) && (r < 0.55)) {
00049             AVERAGE += r;
00050             num_samples++;
00051         }
00052     }
00053 
00054     AVERAGE /= NUM_SAMPLES;
00055 
00056     num_samples = 0;
00057     pc.printf("Average = %f\n",AVERAGE);
00058 
00059 
00060 // Now start sampling series of 500,000
00061 // acculumating the errors seen in each range
00062     pc.printf("Profiling %d samples\n",SAMPLE_BLOCKS*NUM_SAMPLES);
00063 
00064 
00065     for (int j=0; j < SAMPLE_BLOCKS ; j++) {
00066 
00067         t.reset();
00068         t.start();
00069 
00070         for (int i = 0; i < NUM_SAMPLES ; i++) {
00071             float a = ain.read();
00072 
00073 
00074             if (a == 1.0) {
00075                 num_spike++;    // > 2048 lsb
00076             } else if (a > (AVERAGE + 0.2500)) {
00077                 num_1024++;    // > 1024 lsb
00078             } else if (a > (AVERAGE + 0.0625)) {
00079                 num_512++;    // > 512 lsb
00080             } else if (a > (AVERAGE + 0.0312)) {
00081                 num_256++;    // > 256 lsb
00082             } else if (a > (AVERAGE + 0.0312)) {
00083                 num_128++;    // > 128 lsb
00084             } else if (a > (AVERAGE + 0.0156)) {
00085                 num_64++;    // > 64 lsb
00086             } else if (a > (AVERAGE + 0.0078)) {
00087                 num_32++;    // > 32 lsb
00088             } else if (a > (AVERAGE + 0.0039)) {
00089                 num_16++;    // > 16 lsb
00090             } else if (a > (AVERAGE + 0.0019)) {
00091                 num_8++;    // > 8 lsb
00092             } else if (a > (AVERAGE + 0.0009)) {
00093                 num_4++;    // > 8 lsb
00094             }
00095 
00096             num_samples++;
00097         }
00098         t.stop();
00099 
00100         if (j==0) {
00101             pc.printf("Samples\t");
00102             pc.printf("4\t");
00103             pc.printf("8\t");
00104             pc.printf("16\t");
00105             pc.printf("32\t");
00106             pc.printf("64\t");
00107             pc.printf("128\t");
00108             pc.printf("256\t");
00109             pc.printf("512\t");
00110             pc.printf("1024\t");
00111             pc.printf("Spikes\t");
00112             pc.printf("Time\n");
00113         }
00114 
00115 
00116         // Every 500,000 print the results
00117         pc.printf("%d\t",num_samples);
00118         pc.printf("%d\t",num_4);
00119         pc.printf("%d\t",num_8);
00120         pc.printf("%d\t",num_16);
00121         pc.printf("%d\t",num_32);
00122         pc.printf("%d\t",num_64);
00123         pc.printf("%d\t",num_128);
00124         pc.printf("%d\t",num_256);
00125         pc.printf("%d\t",num_512);
00126         pc.printf("%d\t",num_1024);
00127         pc.printf("%d\t",num_spike);
00128         pc.printf("%fs\n",t.read());
00129     }
00130 
00131     pc.printf("==== Test Complete ====\n");
00132 }