Learning IR remotes with the VS1838B

Elena's VS1838B infrared receiver software can learn the raw timing of buttons from compatible IR remotes instead of requiring a preprogrammed remote protocol. The project was developed and tested on the Raspberry Pi Pico platform, with preliminary Arduino support included in the source.

Title and date

Learning IR remotes with the VS1838B — August 31, 2026

Development stage

Working Raspberry Pi Pico prototype with additional platform support under evaluation.

Goal

Create a reusable IR receiver and remote-code learning tool that can capture an unknown remote, assign readable names to its buttons, and generate source code for use in Elena's firmware.

The learner records raw mark-and-space timing rather than assuming a specific protocol. This allows it to work with compatible infrared remotes from many manufacturers, not only one predefined handset. It does not apply to RF, Bluetooth, or other non-infrared remotes.

Components used

• Raspberry Pi Pico or Raspberry Pi Pico 2 W
• One or more VS1838B active-low demodulating IR receiver modules
• Compatible infrared remote control
• USB connection and serial terminal software
• Shared 3.3 V power and ground

What changed

The IR receiver utility captures unknown button transmissions, measures their timing in microseconds, combines repeated transmissions, and assigns readable button names. Its LIST command generates reusable ir_codes.h and ir_codes.c files for an application.

The software was developed on the Raspberry Pi Pico platform using the Raspberry Pi Pico SDK. Arduino support has been added, but it has not been fully tested on Arduino hardware.

Wiring or schematic

For one VS1838B receiver on a Raspberry Pi Pico or Pico 2 W:

VS1838B connection	Raspberry Pi Pico connection
VCC	3.3 V
GND	GND
OUT	GPIO 15

Multiple VS1838B modules were tested facing in different directions. All modules used the same 3.3 V power source and common ground, and their signal lines were tied together at GPIO 15. This provides wider directional coverage while consuming only one Pico I/O pin.

The receiver modules used in this test have active-low demodulated outputs. Before tying signal outputs together, verify the pin labels, operating voltage, and output type of the exact module being installed; VS1838B carrier boards do not always use the same physical pin order or output circuitry.

For the Arduino implementation, the default receiver input is digital pin 2. The Arduino pin can be changed with IR_RX_PIN, and the Pico capture pin can be changed with IR_GPIO.

Software changes

The complete source code, Raspberry Pi Pico project, Arduino sketch, generated-code example, and usage instructions are available in the public repository:

David Harmor's IR Receiver and Remote-Code Learner source code

The normal capture workflow is:

1. Connect to the board's serial interface.
2. Enter CAPTURE.
3. Enter a readable name for the next button.
4. Press that button on the remote.
5. Repeat for the remaining buttons.
6. Enter EXIT, followed by LIST, to generate ir_codes.h and ir_codes.c.

An application calls ir_remote_init() once and repeatedly calls ir_remote_poll() to receive the learned button codes.

Test results

Test	Expected	Observed	Result
Learn buttons from different compatible IR remotes	Capture raw timings without a fixed protocol	Button timings and names were captured	Pass
Generate reusable source	Produce header and implementation sections	ir_codes.h and ir_codes.c were generated	Pass
Decode learned buttons on Raspberry Pi Pico	Return the assigned button name	Learned buttons were recognized	Pass
Use multiple receivers on one signal input	Improve directional coverage without more GPIO pins	Receivers facing different directions worked with tied signal lines	Pass
Arduino compatibility	Compile and operate through the Arduino platform hooks	Support is implemented but hardware testing is incomplete	Not fully tested

Problems encountered

A single IR receiver has a limited field of view, which makes remote operation unreliable when Elena is approached from different directions. Supporting multiple receivers with separate GPIO inputs would also consume pins needed by other sensors and controls.

IR remotes use different protocols and timing patterns, so a decoder written for only one standard would unnecessarily restrict the remotes that could be used.

Solution

Place multiple compatible VS1838B receivers around Elena, power them from the same 3.3 V rail, connect them to the common ground, and tie their tested-compatible active-low signal outputs to one GPIO input. The software captures raw timing data and generates a code table for the actual remote being used.

Photographs/video

Photographs of the final receiver placement and a demonstration video will be added after the sensors are mounted on Elena's chassis.

Next steps

1. Test the Arduino implementation on representative Arduino boards.
2. Record the exact VS1838B carrier-module part numbers and pin order used on Elena.
3. Mount receivers to provide front, side, and rear coverage.
4. Test reception range and reliability under indoor lighting and sunlight.
5. Integrate the generated button table into Nolena's command handling.