CHQ1838 IR Sensor

Using Arduino Sensors
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I have a Nano, CHQ1838 IR sensor & IR LED (unknown p/n / specs). I'm trying to use it as a light curtain.
IR Detected - Pin 13 high (On board LED)
beam broken by object, Pin 7 High, Pin 13 Low

I'm using the Arduino-IRremote library & started with the example given in the library authors blog

I've also added the resistors/capacitor indicated in the IR sensor data sheet circuit, with no difference in operation.

On power up, the sensor detect IR for ~1s (no scope to view, but it is about 1s). After that, it stops detecting IR, until you cover the sensor or unplug the LED, then it will detect for 1s. If I plug/unplug the LED as fast as I can, it responds instantly as far as I can tell.

Is the receiver sensing 'noise' since the LED is on all the time? I've tried various ideas to turn the LED off for 600us, but haven't found anything that works (irsend.mark(600), irsend.space(600), delay(1), etc). Either I get no effect, or I get NO detected IR.

Any suggestions, I have a feeling the answer is simple, but I'm not seeing it.

//Arduino Nano v3.0
//CHQ1338 IR Receiver - IR Receive = LOW
#include <IRremote.h>

#define PIN_IR 3              //LED + 470ohm
#define PIN_DETECT 2       //CHQ1838, Pin 3
#define PIN_STATUS 13     //On Board LED
#define PIN_VALVE 7         //Pnuematic Valve  (LED Simulating)

IRsend irsend;
void setup()
{
  pinMode(PIN_DETECT, INPUT);
  pinMode(PIN_STATUS, OUTPUT);
  irsend.enableIROut(38);     //PWM IR LED @38khz
  irsend.mark(0);  
}

void loop() {
  digitalWrite(PIN_STATUS, !digitalRead(PIN_DETECT));     //IR Detected = LED ON
  digitalWrite(PIN_VALVE, digitalRead(PIN_DETECT));        //IR NOT Detected = Valve cycle
  delay(20); //Cyl extend
  digitalWrite(PIN_VALVE, 0);//Turn valve off
  delay(20);//Cyl retract
}
2

For reference, I found the answer to my problems in the comments in the above blog.

#include

#define PIN_IR 3
#define PIN_DETECT 7
#define PIN_STATUS 13
// ms that beam will be disabled
#define BEAM_OFF_TIME 60

IRsend irsend;

int count;
boolean detected = false;

unsigned long timeStamp = 0;

void setup()
{
Serial.begin(57600);
pinMode(PIN_IR, OUTPUT);
pinMode(PIN_DETECT, INPUT);
pinMode(PIN_STATUS, OUTPUT);
irsend.enableIROut(38);
}

void loop() {

if (millis()-timeStamp > BEAM_OFF_TIME) {
detected = false;
irsend.enableIROut(38);
}
if (!detected) {
irsend.space(0);
delay(1);
irsend.mark(0);
delay(1);
detected = !digitalRead(PIN_DETECT);
if (detected) {
digitalWrite(PIN_IR, LOW);
}
digitalWrite(PIN_STATUS, detected);
Serial.println(detected);
timeStamp = millis();
}

}

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