IR Receiver

What it is

A remote does not flash a light at you. It switches an infrared LED on and off 38,000 times a second and sends its bits by turning that flicker on and off, because a bare pulse of light looks like sunlight and a 38 kHz tone does not.

The TK15 carries the part that undoes it: a Vishay TSOP18138, a photodiode, amplifier, 38 kHz filter and demodulator in one package, lying flat in a steel shield and looking out through its X-shaped window. What reaches your pin is the message with the carrier stripped off: SIGNAL is HIGH at rest and LOW while a burst arrives.

The IRremote library times those lows and hands your sketch a protocol, an address and a command. Neither number is standard: they belong to the remote that sent them.

The boxes

The TK15 comes in the IR Remote Mastery Kit with the TK16 sender: three of each and three 17-button remotes. The remotes take two AAA cells each, not included.

Which pin is which

Parts up, header at the bottom, left to right:

The back prints TK15 IR RECEIVER instead of pin names. Turned over, the square pad is on the right, and it is still GND.

Wiring, in three lines

1. GND to your board's GND.
2. VCC to 5V on an Uno, 3V3 on an ESP32, ESP32-S3 or Pico.
3. SIGNAL to a digital pin: D2 on an Uno, GPIO 23 on an ESP32, GPIO 9 on an ESP32-S3, GP16 on a Pico.

Leave NC unconnected.

Example

#include <IRremote.hpp>   // IRremote by shirriff, z3t0 and ArminJo

// Uno: 2. ESP32: 23. ESP32-S3: 9. Pico: 16.
const int IR_RX_PIN = 2;

void setup() {
  Serial.begin(115200);
  IrReceiver.begin(IR_RX_PIN, DISABLE_LED_FEEDBACK);
}

void loop() {
  if (!IrReceiver.decode()) return;
  IRData &d = IrReceiver.decodedIRData;
  if (d.flags & IRDATA_FLAGS_IS_REPEAT) {
    Serial.println("[repeat]");        // a held button
  } else {
    Serial.print("address=0x");
    Serial.print(d.address, HEX);
    Serial.print("  command=0x");
    Serial.println(d.command, HEX);
  }
  IrReceiver.resume();    // nothing else decodes until this runs
}

# mpremote mip install "github:peterhinch/micropython_ir/ir_rx"
import time
from machine import Pin
from ir_rx.nec import NEC_8

# ESP32: 23. ESP32-S3: 9. Pico: 16.
IR_RX_PIN = 9

def got(command, address, ctrl):
    if command < 0:                    # a repeat frame
        print("[repeat]")
    else:
        print("address=0x%02x  command=0x%02x" % (address, command))

ir = NEC_8(Pin(IR_RX_PIN, Pin.IN), got)
while True:
    time.sleep_ms(500)

Where to start

The handbook below covers both boards and the remote, in eleven short articles, each with a working figure. Your first key code is the one to run first: every project with this block begins by finding out what your own remote sends. The carrier is the trick explains the rest of the behaviour on this page, and how far, and how wide is the honest answer about range.