Using a Game Boy Color as an Air Conditioner Remote Control

It would be unfathomable to release a new video game console without network connectivity today. But in 1998, when Nintendo launched the Game Boy Color (GBC), Wi-Fi was still experimental cutting-edge technology. It would have been incredibly expensive to include, would have destroyed battery life, and would have made the GBC huge. But Nintendo still wanted to include some hardware to enable communication between GBC consoles and JinGen Lim took advantage of that hardware to repurpose his GBC as a remote control for his air conditioner.

Lim received a beautiful red GBC as a gift and wanted a purpose for it beyond just gaming. He decided he could use a new remote control for his mini-split air conditioner unit. Like most remote controls, that relied on infrared communication and Nintendo just happened to include an infrared emitter and receiver on the GBC for communication.

Before proceeding, Lim first needed to determine if this idea was possible. Nintendo designed the GBC’s IR emitter to transfer small amounts of data to other consoles, such as when trading Pokémon with a friend, but could it modulate that emitter in any arbitrary sequence?

Lim found the proof he needed in the Mission: Impossible (2000) game for the GBC. Reviews for that game weren’t great, but it includes several spying-adjacent utilities that players can use. Some of those, like a “secret” address book, are similar to what you’d find on a PDA (Personal Digital Assistant) from the era. But others are more unique and that includes IR programs. There is even a function for recording and playing back infrared sequences, just like a universal remote. Learning that was enough for Lim to verify that his idea would work.

With that knowledge, Lim proceeded with programming his own custom “game” and making a custom GBC cartridge for it. Original GBC cartridges almost never had rewritable ROM chips, but modern bootleg usually cartridges do. Lim was able to grab one of those bootleg cartridges for a few bucks and could then flash his own ROM using a GBxCart RW. The “game” is a simple interface that transmits a specific infrared code, like the one for “turn the temperature up,” when the user presses the corresponding GBC button.

The final challenge was learning the infrared codes. Lim’s air conditioner is a model from National (a Panasonic brand common in Asia for decades), but code information wasn’t available online. So, Lim soldered a small wire to the original remote’s infrared transmitter and connected that to an oscilloscope. That let him record the pulses sent after each button press. He could then plug those codes into his custom GBC game.

Now Lim has what is likely the coolest air conditioner remote control in the world.