1. #define TSL_FREQ_PIN 2 // output use digital pin2 for interrupt  
   2. #define TSL_S0       5  
   3. #define TSL_S1       6  
   4. #define TSL_S2       7  
   5. #define TSL_S3       8  
   
      1. unsigned long pulse_cnt = 0;  
   2.   
   3. void setup() {  
   4.   
   5.   // attach interrupt to pin2, send output pin of TSL230R to arduino 2  
   6.   // call handler on each rising pulse  
   7.   
   8.  attachInterrupt(0, add_pulse, RISING);  
   9.   
  10.  pinMode(TSL_FREQ_PIN, INPUT);  
  11.  pinMode(TSL_S0, OUTPUT);  
  12.  pinMode(TSL_S1, OUTPUT);  
  13.  pinMode(TSL_S2, OUTPUT);  
  14.  pinMode(TSL_S3, OUTPUT);  
  15.   
  16.  digitalWrite(TSL_S0, HIGH);  
  17.  digitalWrite(TSL_S1, LOW);  
  18.  digitalWrite(TSL_S2, HIGH);  
  19.  digitalWrite(TSL_S3, HIGH);  
  20. }  
  21.   
  22. void loop() {  
  23.   
  24. }  
  25.   
  26. void add_pulse() {  
  27.   
  28.   // increase pulse count  
  29.  pulse_cnt++;  
  30.  return;  
  31. }