First of all, I know there are probably 50 different threads on this topic, but I can't find one that addresses my problem. I am trying to make a simple break beam sensor using an Arduino Uno, a 950 nm IR LED, and a TSOP 38238 sensor ( IR (Infrared) Receiver Sensor [TSOP38238] : ID 157 : $1.95 : Adafruit Industries, Unique & fun DIY electronics and kits ). I have it wired with the proper resistor, and I know that the sensor and LED are both working and making contact with each other. I know that the LED needs to be PWM'd at 38khz in order for the sensor to read it properly, and I think I found a chunk of code that will let me do that.
/* Code to pulse pin 3 with a modulated signal
* Can be used to drive an IR LED to keep a TSOP IR reciever happy
* This allows you to use a modulated reciever and a continious beam detector
* By Mike Cook Nov 2011 - Released under the Open Source licence
*/
volatile byte pulse = 0;
ISR(TIMER2_COMPB_vect){ // Interrupt service routine to pulse the modulated pin 3
pulse++;
if(pulse >= 8) { // change number for number of modulation cycles in a pulse
pulse =0;
TCCR2A ^= _BV(COM2B1); // toggle pin 3 enable, turning the pin on and off
}
}
void setIrModOutput(){ // sets pin 3 going at the IR modulation rate
pinMode(3, OUTPUT);
TCCR2A = _BV(COM2B1) | _BV(WGM21) | _BV(WGM20); // Just enable output on Pin 3 and disable it on Pin 11
TCCR2B = _BV(WGM22) | _BV(CS22);
OCR2A = 51; // defines the frequency 51 = 38.4 KHz, 54 = 36.2 KHz, 58 = 34 KHz, 62 = 32 KHz
OCR2B = 26; // deines the duty cycle - Half the OCR2A value for 50%
TCCR2B = TCCR2B & 0b00111000 | 0x2; // select a prescale value of 8:1 of the system clock
}
void setup(){
setIrModOutput();
TIMSK2 = _BV(OCIE2B); // Output Compare Match B Interrupt Enable
}
void loop(){
// do something here
}
My problem is reading this code. I found a stock code for reading IR remotes, but I'm really struggling to adapt it to reading my LED.
/* Raw IR decoder sketch!
This sketch/program uses the Arduno and a PNA4602 to
decode IR received. This can be used to make a IR receiver
(by looking for a particular code)
or transmitter (by pulsing an IR LED at ~38KHz for the
durations detected
Code is public domain, check out www.ladyada.net and adafruit.com
for more tutorials!
*/
// We need to use the 'raw' pin reading methods
// because timing is very important here and the digitalRead()
// procedure is slower!
//uint8_t IRpin = 2;
// Digital pin #2 is the same as Pin D2 see
// http://arduino.cc/en/Hacking/PinMapping168 for the 'raw' pin mapping
#define IRpin_PIN PIND
#define IRpin 2
// for MEGA use these!
//#define IRpin_PIN PINE
//#define IRpin 4
// the maximum pulse we'll listen for - 65 milliseconds is a long time
#define MAXPULSE 65000
// what our timing resolution should be, larger is better
// as its more 'precise' - but too large and you wont get
// accurate timing
#define RESOLUTION 20
// we will store up to 100 pulse pairs (this is -a lot-)
uint16_t pulses[100][2]; // pair is high and low pulse
uint8_t currentpulse = 0; // index for pulses we're storing
void setup(void) {
Serial.begin(9600);
Serial.println("Ready to decode IR!");
}
void loop(void) {
uint16_t highpulse, lowpulse; // temporary storage timing
highpulse = lowpulse = 0; // start out with no pulse length
// while (digitalRead(IRpin)) { // this is too slow!
while (IRpin_PIN & (1 << IRpin)) {
// pin is still HIGH
// count off another few microseconds
highpulse++;
delayMicroseconds(RESOLUTION);
// If the pulse is too long, we 'timed out' - either nothing
// was received or the code is finished, so print what
// we've grabbed so far, and then reset
if ((highpulse >= MAXPULSE) && (currentpulse != 0)) {
printpulses();
currentpulse=0;
return;
}
}
// we didn't time out so lets stash the reading
pulses[currentpulse][0] = highpulse;
// same as above
while (! (IRpin_PIN & _BV(IRpin))) {
// pin is still LOW
lowpulse++;
delayMicroseconds(RESOLUTION);
if ((lowpulse >= MAXPULSE) && (currentpulse != 0)) {
printpulses();
currentpulse=0;
return;
}
}
pulses[currentpulse][1] = lowpulse;
// we read one high-low pulse successfully, continue!
currentpulse++;
}
void printpulses(void) {
Serial.println("\n\r\n\rReceived: \n\rOFF \tON");
for (uint8_t i = 0; i < currentpulse; i++) {
Serial.print(pulses[i][0] * RESOLUTION, DEC);
Serial.print(" usec, ");
Serial.print(pulses[i][1] * RESOLUTION, DEC);
Serial.println(" usec");
}
// print it in a 'array' format
Serial.println("int IRsignal[] = {");
Serial.println("// ON, OFF (in 10's of microseconds)");
for (uint8_t i = 0; i < currentpulse-1; i++) {
Serial.print("\t"); // tab
Serial.print(pulses[i][1] * RESOLUTION / 10, DEC);
Serial.print(", ");
Serial.print(pulses[i+1][0] * RESOLUTION / 10, DEC);
Serial.println(",");
}
Serial.print("\t"); // tab
Serial.print(pulses[currentpulse-1][1] * RESOLUTION / 10, DEC);
Serial.print(", 0};");
}
I want to write the code so that if a person walks through my sensor, i simply get an output that says "Broken" in the serial monitor. I am eventually going to time stamp every time the sensor is broken, but that is a different animal for another day. It is also probably worth noting that I am a mechanical engineering student, and this is my first big coding project. I'm working on learning the code, but sort of C++ illiterate right now. Any help would be appreciated.