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Compile warning · library version

Fix IRremote “It seems, that you are using an old version 2.0 code / example”

IRremote 3+/4.x replaced irrecv.decode(&results) and results.value. Use IrReceiver.begin(), decode() and decodedIRData.command — or the codes you saved won’t match.

Arduino UnoArduino NanoESP32ESP8266Updated 3 Nov 2026

Community draft — report a mistake

What you see

OutputOutput
libraries\IRremote\src/IRremote.h:12:2: warning: #warning It seems, that you are using an old version 2.0 code / example. [-Wcpp]
libraries\IRremote\src/IRremote.h:13:2: warning: #warning This version is no longer supported! [-Wcpp]
libraries\IRremote\src/IRremote.h:18:2: warning: #warning Or just downgrade your library to version 2.6.0. [-Wcpp]
Sketch uses 6112 bytes (18%) of program storage space. Maximum is 32256 bytes.

--- Serial Monitor ---
Thank you for using the IRremote library!
It seems, that you are using an old version 2.0 code / example.
This version is no longer supported!

IRremote 3.0 rewrote the receive API, and 4.x keeps only a thin shim for 2.x sketches. The #warning lines (and the banner printed on the Serial Monitor) are the library telling you it is running old-style code that may not match your remote’s codes.

#include <IRremote.hpp>

void setup() {
  Serial.begin(9600);
  IrReceiver.begin(11, ENABLE_LED_FEEDBACK);
}

void loop() {
  if (IrReceiver.decode()) {
    Serial.println(IrReceiver.decodedIRData.command, HEX);   // e.g. 45 for button 1
    IrReceiver.resume();
  }
}

Quick fix — try in order

  1. 1

    Include IRremote.hpp and use IrReceiver

    #include <IRremote.hpp>, then in setup() IrReceiver.begin(11, ENABLE_LED_FEEDBACK);. No IRrecv irrecv(11) or decode_results object.

  2. 2

    Read decodedIRData

    if (IrReceiver.decode()) { uint8_t cmd = IrReceiver.decodedIRData.command; IrReceiver.resume(); }.

  3. 3

    Re-learn your remote’s codes

    v4 reports the NEC command byte (e.g. 0x45), not the old 32-bit value (e.g. 0xFFA25D). Print IrReceiver.printIRResultShort(&Serial); and note the new codes.

  4. 4

    Or downgrade for an old project

    Library Manager → IRremote → 2.6.0 makes 2.x code work unchanged — the library itself suggests it. Fine for a one-off, not for new projects.

Why it happens

It compiles — why change anything?

The old decode(&results) is kept only as a compatibility shim that fills value with the old MSB-first codes. Many remotes then give different or zero values, so if (results.value == 0xFFA25D) never matches.

results.value is always 0xFFFFFFFF

That was the NEC “repeat” code in v2. v4 sets a repeat flag instead: check IrReceiver.decodedIRData.flags & IRDATA_FLAGS_IS_REPEAT.

ESP32 compile errors with old IRremote

IRremote 2.x doesn’t support ESP32 core 3.x. Use 4.x.

Board-specific notes

Arduino Uno: Receiver OUT to pin 11 (or any pin you pass to begin). Project: IR remote relay.

Parts: VS1838B IR receiver — pinout varies between modules; check before powering.

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