Diff: main.cpp

Revision:

1:bdd134268a52

Parent:

0:62a007afbcbf

Child:

2:4c61969f2207

--- a/main.cpp	Thu Dec 01 16:37:07 2011 +0000
+++ b/main.cpp	Fri Dec 02 10:04:15 2011 +0000
@@ -1,14 +1,13 @@
 #include "mbed.h"
 
-#define NUM_SAMPLES 500000
+#define NUM_SAMPLES 500000 // size of sample series
 
-DigitalOut myled(LED1);
 Serial pc(USBTX,USBRX);
 
 AnalogIn ain(p17);
 
-Timer t;
-
+// initialise error counters
+int num_4;
 int num_8;
 int num_16;
 int num_32;
@@ -19,13 +18,13 @@
 int num_1024;
 int num_2048;
 
-
 int main() {
 
     pc.baud(115200);
-    
+
     int num_samples = 0;
 
+    num_4 = 0;
     num_8 = 0;
     num_16 = 0;
     num_32 = 0;
@@ -36,95 +35,67 @@
     num_1024 = 0;
     num_2048 = 0;
 
-/*
-    while (1) {
-        pc.printf("%f\n",ain.read());
-//        wait(0.1);
-    }
-*/
 
-
-
-
-// do a calibration
-
+// Take the average over 500,000 samples
+// This is because teh bias to 1.65v has a tolerance
     float AVERAGE = 0.5;
 
-    // taking an average    
     pc.printf("Taking an average over %d samples\n",NUM_SAMPLES);
     while (num_samples < NUM_SAMPLES) {
-     float r = ain.read();
-     
-     if ((r > 0.49) && (r < 0.51)) {
-     AVERAGE = (AVERAGE + r) /2.0;
-     num_samples++;
-     }
-    
+        float r = ain.read();
+
+        if ((r > 0.49) && (r < 0.51)) {
+            AVERAGE = (AVERAGE + r) /2.0;
+            num_samples++;
+        }
     }
+    num_samples = 0;
     pc.printf("Average = %f\n",AVERAGE);
 
-        
+    
+// Now start sampling series of 500,000
+// acculumating the errors seen in each range 
+    while (1) {
 
-    pc.printf("Reading floats\n");
-    num_samples = 0;
-    t.reset();
-    t.start();
-    
-    while (num_samples < NUM_SAMPLES) {
-        float a = ain.read();
-
+        for (int i = 0; i < NUM_SAMPLES ; i++) {
+            float a = ain.read();
 
-        if (a > (AVERAGE + 0.5000)) 
-            {num_2048++;} // > 2048 lsb
-        else if (a > (AVERAGE + 0.2500)) 
-            {num_1024++;} // > 1024 lsb
-        else if (a > (AVERAGE + 0.0625)) 
-            {num_512++;} // > 512 lsb
-        else if (a > (AVERAGE + 0.0312)) 
-            {num_256++;} // > 256 lsb
-        else if (a > (AVERAGE + 0.0312)) 
-            {num_128++;} // > 128 lsb
-        else if (a > (AVERAGE + 0.0156)) 
-            {num_64++;} // > 64 lsb
-        else if (a > (AVERAGE + 0.0078)) 
-            {num_32++;} // > 32 lsb
-        else if (a > (AVERAGE + 0.0039)) 
-            {num_16++;} // > 16 lsb
-        else if (a > (AVERAGE + 0.0019)) 
-            {num_8++;} // > 8 lsb
-        
-        num_samples++;
+            if (a > (AVERAGE + 0.5000)) {
+                num_2048++;    // > 2048 lsb
+            } else if (a > (AVERAGE + 0.2500)) {
+                num_1024++;    // > 1024 lsb
+            } else if (a > (AVERAGE + 0.0625)) {
+                num_512++;    // > 512 lsb
+            } else if (a > (AVERAGE + 0.0312)) {
+                num_256++;    // > 256 lsb
+            } else if (a > (AVERAGE + 0.0312)) {
+                num_128++;    // > 128 lsb
+            } else if (a > (AVERAGE + 0.0156)) {
+                num_64++;    // > 64 lsb
+            } else if (a > (AVERAGE + 0.0078)) {
+                num_32++;    // > 32 lsb
+            } else if (a > (AVERAGE + 0.0039)) {
+                num_16++;    // > 16 lsb
+            } else if (a > (AVERAGE + 0.0019)) {
+                num_8++;    // > 8 lsb
+            } else if (a > (AVERAGE + 0.0009)) {
+                num_4++;    // > 8 lsb
+            }
+
+            num_samples++;
+        }
+
+        // Every 500,000 print the results
+        pc.printf("%d\t",num_samples);
+        pc.printf("%d\t",num_4);
+        pc.printf("%d\t",num_8);
+        pc.printf("%d\t",num_16);
+        pc.printf("%d\t",num_32);
+        pc.printf("%d\t",num_64);
+        pc.printf("%d\t",num_128);
+        pc.printf("%d\t",num_256);
+        pc.printf("%d\t",num_512);
+        pc.printf("%d\t",num_1024);
+        pc.printf("%d\n",num_2048);
     }
-    
-    t.stop();
-    pc.printf("Time taken for %d samples was %fs\n",NUM_SAMPLES,t.read());
-    pc.printf("over 8 lsb = %d\n",num_8);
-    pc.printf("over 16 lsb = %d\n",num_16);
-    pc.printf("over 32 lsb = %d\n",num_32);
-    pc.printf("over 64 lsb = %d\n",num_64);
-    pc.printf("over 128 lsb = %d\n",num_128);
-    pc.printf("over 256 lsb = %d\n",num_256);
-    pc.printf("over 512 lsb = %d\n",num_512);
-    pc.printf("over 1024 lsb = %d\n",num_1024);
-    pc.printf("over 2048 lsb = %d\n",num_2048);
-
-
-
-
-
-/*
-    pc.printf("Reading _u16\n");
-    num_samples = 0;
-    t.reset();
-    t.start();
-    while (num_samples < NUM_SAMPLES) {
-        int a = ain.read_u16();
-        num_samples++;
-    }
-    t.stop();
-    pc.printf("Time taken for %d samples was %fs\n",NUM_SAMPLES,t.read());
-
-*/
-
-
 }