Diff: main.cpp

Revision:

0:93964709b7a6

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp	Tue Dec 06 16:23:00 2011 +0000
@@ -0,0 +1,71 @@
+/*
+ * The program try to test the phenomenon as mentioned in
+ * http://mbed.org/users/chris/notebook/Getting-best-ADC-performance/
+ *
+ *  a) Unused ADC pins are either tied to ground, or declared as DigitalOut
+ *  b) Quality of signal source, including low noise design techniques such 
+ *     as filtering. 
+ *  c) Reduce debugging communication via USB
+ */
+ 
+#include "mbed.h"
+
+#define   SSIZE 100
+
+AnalogIn  ain(p20);
+BusOut    unused(p15,p16,p17,p18,p19);  // Make unused analog pin to DigitalOut
+
+float     value[SSIZE];
+float     max;
+float     min;
+double    itg;
+
+void printNow()
+{
+  time_t    s;
+  char      buffer[20];
+
+  s = time(NULL);
+  strftime(buffer, sizeof(buffer), "%Y-%m-%d %H:%M:%S", localtime(&s));
+  printf("%s\n", buffer);
+}
+
+void printSecNow()
+{
+  time_t    s;
+  s = time(NULL);
+  printf("%d\n", s);
+}
+
+int main() 
+{
+  set_time(1323180910);
+
+  while (1)
+  {
+    //printNow();
+    printf("\n-----------------\n");
+    printSecNow();
+    max = itg = 0.0;
+    min = 3.3;
+    // Sample before printing to avoid debug communucation
+    for (int i=0; i<SSIZE; i++)
+    {
+      value[i] = ain;
+      if (value[i] > max) max = value[i];
+      if (value[i] < min) min = value[i];
+      itg += value[i];
+    }
+    printSecNow();
+    
+    // Now print out
+    for (int i=0; i<SSIZE; i++)
+    {
+      printf("%0.3f ", value[i]*3.3);  
+    }
+    printf("\n");
+    printf("max=%0.3f, min=%0.3f, avg=%0.3f\n", 
+           max*3.3, min*3.3, 3.3*itg/SSIZE);
+    wait(10);
+  }
+}