git.piffa.net Git - arduino/blob - books/ArduinoNextSteps-master/ArduinoNextSteps/timer_interrupt_example/timer_interrupt_example.ino

   1 #include <TimerOne.h>
   2
   3 double v[11];
   4
   5 void setup()
   6 {
   7   // Initialize the digital pin as an output.
   8   // Pin 13 has an LED connected on most Arduino boards
   9   pinMode(12, OUTPUT);
  10   initFilter();
  11   Serial.begin(115200);
  12   Timer1.initialize(5000);
  13   Timer1.attachInterrupt( timerIsr ); // attach the service routine here
  14 }
  15
  16 void loop()
  17 {
  18   // Main code loop
  19   // TODO: Put your regular (non-ISR) logic here
  20 }
  21
  22 /// --------------------------
  23 /// Custom ISR Timer Routine
  24 /// --------------------------
  25 void timerIsr()
  26 {
  27     digitalWrite(12, HIGH);
  28     int raw = analogRead(A0);
  29     double input = (double)raw;
  30     double filtered = filterStep(input);
  31     Serial.print(input);
  32     Serial.print(" ");
  33     Serial.println(filtered);
  34     digitalWrite(12, LOW);
  35 }
  36
  37 // Sample f 200Hz, band stop 49-50Hz
  38 // http://www.schwietering.com/jayduino/filtuino/index.php?characteristic=bu&passmode=bs&order=3&usesr=usesr&sr=200&frequencyLow=47&noteLow=&frequencyHigh=53&noteHigh=&pw=pw&calctype=double&run=Send
  39 // Band stop butterworth filter order=3 alpha1=0.235 alpha2=0.265
  40 void initFilter()
  41 {
  42   for(int i=0; i <= 10; i++)
  43   {
  44     v[i]=0.0;
  45   }
  46 }
  47
  48
  49 double filterStep(double x)
  50 {
  51                         v[0] = v[1];
  52                         v[1] = v[2];
  53                         v[2] = v[3];
  54                         v[3] = v[4];
  55                         v[4] = v[5];
  56                         v[5] = v[6];
  57                         v[6] = (8.27971295622e-1 * x)
  58                                  + ( -0.6855359773 * v[0])
  59                                  + ( -0.0000000000 * v[1])
  60                                  + ( -2.3146825811 * v[2])
  61                                  + ( -0.0000000000 * v[3])
  62                                  + ( -2.6235518066 * v[4])
  63                                  + ( -0.0000000000 * v[5]);
  64                         return
  65                                  (v[0] + v[6])
  66                                 +3 * (v[2] + v[4]);
  67 }
  68
  69