Laser/IR code catcher

I put together a 'special' box to grab some IR laser coded transmissions (eg like TV remotes)

I needed something easily fieldable, so grabbing the defunct camera trigger box (with built in power switch, status LED and signal LED :) ) I velcro'ed a mini breadboard and ATMega328 board in.

The breadboard consists of a regulated 5V supply, a regulated 3V3 supply (for the SD card), an IR phototransistor/amplifier (nabbed from an old TV tuner box) and some voltage level shifters to allow the 5V MCU to talk with the SD card

Code after the break...














/*
 * SD card attached to SPI bus as follows:
 ** MOSI - pin 11
 ** MISO - pin 12
 ** CLK - pin 13
 ** CS - pin 10
 */
 /***************************************************************/
// Includes
#include <SD.h>
#include <avr/interrupt.h>
#include <avr/io.h>

#define TIMER_RESET  TCNT1 = 0
#define SAMPLE_SIZE  64

/***************************************************************/
// Variable declaration
int IRpin = 2;
unsigned int TimerValue[SAMPLE_SIZE];
char direction[SAMPLE_SIZE];
byte change_count;
long time;

File myFile;

void setup() {
  Serial.begin(115200);
  Serial.println("Analyze IR Remote");
  TCCR1A = 0x00;          // COM1A1=0, COM1A0=0 => Disconnect Pin OC1 from Timer/Counter 1 -- PWM11=0,PWM10=0 => PWM Operation disabled
  // ICNC1=0 => Capture Noise Canceler disabled -- ICES1=0 => Input Capture Edge Select (not used) -- CTC1=0 => Clear Timer/Counter 1 on Compare/Match
  // CS12=0 CS11=1 CS10=1 => Set prescaler to clock/64
  TCCR1B = 0x03;          // 16MHz clock with prescaler means TCNT1 increments every 4uS
  // ICIE1=0 => Timer/Counter 1, Input Capture Interrupt Enable -- OCIE1A=0 => Output Compare A Match Interrupt Enable -- OCIE1B=0 => Output Compare B Match Interrupt Enable
  // TOIE1=0 => Timer 1 Overflow Interrupt Enable
  TIMSK1 = 0x00;         
  pinMode(IRpin, INPUT);
  pinMode(3, OUTPUT);

  //SD card initialisation
  pinMode(10, OUTPUT);
  if (!SD.begin(10)) {
    Serial.println("SD card initialization failed!");
    return;
  }
 
  Serial.println("SD card initialization done.");
  myFile = SD.open("IR_cap.txt", FILE_WRITE);
  if (myFile)
  {
      myFile.println("IR_cap recording");
  } else {
    // if the file didn't open, print an error:
    Serial.println("error opening test.txt");
  }
 
  //safely close the file 
  myFile.close();
 
}

void loop()
{
  Serial.println("Waiting...");
  change_count = 0;
  while(digitalRead(IRpin) == HIGH) {}
 
  digitalWrite(3, HIGH); 
 
  TIMER_RESET;
  TimerValue[change_count] = TCNT1;
  direction[change_count++] = '1';
 
  while (change_count < SAMPLE_SIZE)
  {
    if (direction[change_count-1] == '1') {
      while(digitalRead(IRpin) == LOW) {}
      TimerValue[change_count] = TCNT1;
      direction[change_count++] = '0';
    } else {
      while(digitalRead(IRpin) == HIGH) {}
      TimerValue[change_count] = TCNT1;
      direction[change_count++] = '1';
    }
  }
 
  change_count = 0;
  time = (long) TimerValue[change_count] * 4;
 
  print_to_SD();
  //print_to_serial();
 
  digitalWrite(3, LOW);
 
}

void print_to_serial()
{
  Serial.println("Bit stream detected!");
  Serial.print(time);
  Serial.print("\t");
  Serial.println(direction[change_count++]);
  while (change_count < SAMPLE_SIZE) {
    time = (long) TimerValue[change_count] * 4;
    Serial.print(time);
    Serial.print("\t");
    Serial.println(direction[change_count-1]);
    Serial.print(time);
    Serial.print("\t");
    Serial.println(direction[change_count++]);   
  }
  Serial.println("Bit stream end!");
 
}

void print_to_SD()
{
 
  myFile = SD.open("IR_cap.txt", FILE_WRITE);
  if (myFile)
  {
    myFile.println("IR Bit stream");
    myFile.print(time);
    myFile.print(" , ");
    myFile.println(direction[change_count++]);
    while (change_count < SAMPLE_SIZE) {
      time = (long) TimerValue[change_count] * 4;
      myFile.print(time);
      myFile.print(" , ");
      myFile.println(direction[change_count-1]);
      myFile.print(time);
      myFile.print(" , ");
      myFile.println(direction[change_count++]);   
    }
    myFile.println("IR Bit stream end");
  } else {
    // if the file didn't open, print an error:
    //Serial.println("error opening test.txt");
  }
 
  //safe close the SD connection
  myFile.close();
  delay(2000);
 
}