Raspberry Pi Pico IR Receiver Simulator: Wiring, Code and a Live Circuit
This is a 38 kHz IR receiver wired to a Raspberry Pi Pico with a remote control beside it, decoded live with the IRremote library: open it in the editor, press a button on the remote, and the serial monitor prints its command code.
Three wires to the receiver: power, GND, and OUT to GP15 (physical pin 20). The remote speaks NEC, the protocol of most cheap kit remotes.
- 3.3 V logic
- Library: IRremote.hpp
- OUT on GP15 (physical pin 20)
- NEC protocol, 38 kHz
Wiring the IR Receiver to the Raspberry Pi Pico
Every connection in the circuit above, with the board’s own pin names.
| IR Receiver pin | Raspberry Pi Pico pin | Why |
|---|---|---|
| VCC | 3V3(OUT) | The VS1838B-style receiver runs from 2.7 to 5.5 V. |
| GND | GND | Ground. |
| OUT | GP15 (physical pin 20) | Low while a 38 kHz burst arrives, high otherwise: the demodulated code. |
| IR (light) | The remote | In the editor the infrared light path is drawn as a gray wire from the remote. |
Power the receiver from 3V3 on the Raspberry Pi Pico: its output then swings to 3.3 V, the board’s own level. Fed from 5 V, its output would idle at 5 V on a 3.3 V pin.
Pins to leave alone on the Raspberry Pi Pico
The numbers in the code are GP numbers, not the physical pin numbers printed beside the header: GP15 is pin 20. GP23 to GP25 are used on the board itself, and GP25 is the LED.
On a real bench
Solder headers on the Pico and press it into the breadboard across the center channel; the IR Receiver goes in beside it. GND pins sit every fifth pin down both sides (pins 3, 8, 13, 18 and so on), so there is always one close. The first upload needs BOOTSEL held while plugging in.
The code
The sketch the circuit above runs. Open it in the editor, change a line and press Run: it compiles in your browser.
#include <IRremote.hpp>
const int IR_PIN = 15; // OUT, GP15 (physical pin 20)
void setup() {
Serial.begin(115200);
IrReceiver.begin(IR_PIN);
Serial.println("Point the remote and press a button");
}
void loop() {
if (IrReceiver.decode()) {
if (!(IrReceiver.decodedIRData.flags & IRDATA_FLAGS_IS_REPEAT)) {
Serial.print("Command: 0x");
Serial.println(IrReceiver.decodedIRData.command, HEX);
}
IrReceiver.resume(); // ready for the next one
}
}
IrReceiver.begin(IR_PIN) starts the IRremote library listening on the pin. decode() returns true once a whole code has arrived, and decodedIRData.command holds the button’s command byte, 0x47 for the button pressed in this demo.
Holding a button makes an NEC remote send short repeat frames, which the library flags with IRDATA_FLAGS_IS_REPEAT. The sketch prints only the first frame of each press. resume() must be called after each code or nothing more is decoded.
Serial.begin(115200) opens the serial monitor. Serial is the USB port at 115200 baud in this sketch; on a real Pico it appears once the board has enumerated.
Common mistakes with the IR Receiver on the Raspberry Pi Pico
Old IRremote code
Sketches written for IRremote 2.x use IRrecv irrecv(pin), irrecv.enableIRIn() and results.value. Version 3 and later use IrReceiver and decodedIRData, as here. Mixing the two is the most common reason an IR sketch will not compile.
Forgetting resume()
After decode() returns true, the library holds the code until resume() is called. Leave it out and the first button press is the only one you ever see.
Counting physical pins instead of GP numbers
The sketch says 15, which means GP15, and that is physical pin 20 on the header. Counting 15 pins down the side lands on a different GPIO, and the part never answers.
Questions and answers
Can I simulate an IR remote with a Raspberry Pi Pico?
Yes. The circuit at the top of this page is a Raspberry Pi Pico with a IR receiver and remote, running in your browser on a simulated RP2040. Click a button on the simulated remote: it sends a real NEC frame, which the receiver demodulates onto the pin. Press Run it in the editor to change the wiring or the code; it is free and needs no account.
How do I find my remote’s codes?
Run this sketch and press each button: the command printed is the code to compare against. Address and command are both in decodedIRData if you need to tell two remotes apart.
Why does every press print FFFFFFFF?
That is the repeat code of an NEC remote as old versions of the library reported it. The current library flags repeats instead, which the sketch checks.
Which receiver is this?
A three-pin 38 kHz demodulating receiver like the VS1838B or TSOP38238. Check the pin order on yours: it differs between makers.
Build your own IR Receiver project
Open this circuit in the editor, change the wiring or the code, and keep your version in a free account.