HM Yoong / Mbed 2 deprecated analogin_noise

To test the analog input noise using potential divider rule. {{/media/uploads/yoonghm/analog_noise.jpg}}

Dependencies:   mbed

main.cpp@0:93964709b7a6, 2011-12-06 (annotated)

Committer:
yoonghm
Date:
Tue Dec 06 16:23:00 2011 +0000
Revision:
0:93964709b7a6
Initial version

Who changed what in which revision?

UserRevisionLine numberNew contents of line
yoonghm 0:93964709b7a6 1 /*
yoonghm 0:93964709b7a6 2 * The program try to test the phenomenon as mentioned in
yoonghm 0:93964709b7a6 3 * http://mbed.org/users/chris/notebook/Getting-best-ADC-performance/
yoonghm 0:93964709b7a6 4 *
yoonghm 0:93964709b7a6 5 * a) Unused ADC pins are either tied to ground, or declared as DigitalOut
yoonghm 0:93964709b7a6 6 * b) Quality of signal source, including low noise design techniques such
yoonghm 0:93964709b7a6 7 * as filtering.
yoonghm 0:93964709b7a6 8 * c) Reduce debugging communication via USB
yoonghm 0:93964709b7a6 9 */
yoonghm 0:93964709b7a6 10
yoonghm 0:93964709b7a6 11 #include "mbed.h"
yoonghm 0:93964709b7a6 12
yoonghm 0:93964709b7a6 13 #define SSIZE 100
yoonghm 0:93964709b7a6 14
yoonghm 0:93964709b7a6 15 AnalogIn ain(p20);
yoonghm 0:93964709b7a6 16 BusOut unused(p15,p16,p17,p18,p19); // Make unused analog pin to DigitalOut
yoonghm 0:93964709b7a6 17
yoonghm 0:93964709b7a6 18 float value[SSIZE];
yoonghm 0:93964709b7a6 19 float max;
yoonghm 0:93964709b7a6 20 float min;
yoonghm 0:93964709b7a6 21 double itg;
yoonghm 0:93964709b7a6 22
yoonghm 0:93964709b7a6 23 void printNow()
yoonghm 0:93964709b7a6 24 {
yoonghm 0:93964709b7a6 25 time_t s;
yoonghm 0:93964709b7a6 26 char buffer[20];
yoonghm 0:93964709b7a6 27
yoonghm 0:93964709b7a6 28 s = time(NULL);
yoonghm 0:93964709b7a6 29 strftime(buffer, sizeof(buffer), "%Y-%m-%d %H:%M:%S", localtime(&s));
yoonghm 0:93964709b7a6 30 printf("%s\n", buffer);
yoonghm 0:93964709b7a6 31 }
yoonghm 0:93964709b7a6 32
yoonghm 0:93964709b7a6 33 void printSecNow()
yoonghm 0:93964709b7a6 34 {
yoonghm 0:93964709b7a6 35 time_t s;
yoonghm 0:93964709b7a6 36 s = time(NULL);
yoonghm 0:93964709b7a6 37 printf("%d\n", s);
yoonghm 0:93964709b7a6 38 }
yoonghm 0:93964709b7a6 39
yoonghm 0:93964709b7a6 40 int main()
yoonghm 0:93964709b7a6 41 {
yoonghm 0:93964709b7a6 42 set_time(1323180910);
yoonghm 0:93964709b7a6 43
yoonghm 0:93964709b7a6 44 while (1)
yoonghm 0:93964709b7a6 45 {
yoonghm 0:93964709b7a6 46 //printNow();
yoonghm 0:93964709b7a6 47 printf("\n-----------------\n");
yoonghm 0:93964709b7a6 48 printSecNow();
yoonghm 0:93964709b7a6 49 max = itg = 0.0;
yoonghm 0:93964709b7a6 50 min = 3.3;
yoonghm 0:93964709b7a6 51 // Sample before printing to avoid debug communucation
yoonghm 0:93964709b7a6 52 for (int i=0; i<SSIZE; i++)
yoonghm 0:93964709b7a6 53 {
yoonghm 0:93964709b7a6 54 value[i] = ain;
yoonghm 0:93964709b7a6 55 if (value[i] > max) max = value[i];
yoonghm 0:93964709b7a6 56 if (value[i] < min) min = value[i];
yoonghm 0:93964709b7a6 57 itg += value[i];
yoonghm 0:93964709b7a6 58 }
yoonghm 0:93964709b7a6 59 printSecNow();
yoonghm 0:93964709b7a6 60
yoonghm 0:93964709b7a6 61 // Now print out
yoonghm 0:93964709b7a6 62 for (int i=0; i<SSIZE; i++)
yoonghm 0:93964709b7a6 63 {
yoonghm 0:93964709b7a6 64 printf("%0.3f ", value[i]*3.3);
yoonghm 0:93964709b7a6 65 }
yoonghm 0:93964709b7a6 66 printf("\n");
yoonghm 0:93964709b7a6 67 printf("max=%0.3f, min=%0.3f, avg=%0.3f\n",
yoonghm 0:93964709b7a6 68 max*3.3, min*3.3, 3.3*itg/SSIZE);
yoonghm 0:93964709b7a6 69 wait(10);
yoonghm 0:93964709b7a6 70 }
yoonghm 0:93964709b7a6 71 }