Diving Deep Into The Game Boy LCD Protocol

[Craig] wanted to make the original Game Boy LCD screen do his bidding so he sniffed out the data protocol that it uses. We were amused when he mentions that there’s an army of people out there looking to build pointless crap as part of a hobby. Guilty. And he goes on to outline why this LCD screen is a great resource for hobbiests.

As you can see in the pinout above, it uses 5V logic, with a 4 MHz data clock. These traits are both very friendly to a wide range if inexpensive microcontrollers. If you know how to address the display it should be very easy to use. Furthermore, the low pin count is thanks the to a 4-shade grayscale screen, limiting the data pins to just two. [Craig] hooked up his Saleae Logic probe to capture communications and walks us through what he discovered. During this process he proved to himself that he had figured out the protocol by exporting captured data from the logic probe and reassembling it into an image on his computer.

22 thoughts on “Diving Deep Into The Game Boy LCD Protocol

  1. This has been widely known to Game Boy hardware developers for a long time now. =\ Besides, how it works is pretty damn obvious even based on the pin names alone. I suppose this might be more useful for beginners to electronics who want to play with this kind of stuff but don’t understand how it would work. Well documented.

  2. The original Gameboy screen was pretty bad, but if you can find a Gameboy Pocket screen, it had the same resolution and protocol, but was slightly bigger and MUCH easier to read (actualy greyscale, not that weird green).

  3. is it only me or is this like oh say 15 years late??? as mentioned above the original screen is terrible only thing i can think of is thats its pretty robust compared to newer screen but you would be better of with GBA screens nowaday. GB original are almost collection items now so there not easy to come by. it would be cheaper/easier to get a GBA screen…

  4. To clarify, I’m more interested in the video data than in reusing the screen. The screen sucks, but it would be cool to pipe the video out to something awesome-er (giant POV display? VGA link cable? etc etc)

  5. @hiroshi

    Backlighting is pretty common on these systems. NeX on 8bitcollective also put a gameboy pocket screen on more than one gameboy. Looks great, especially when backlit.

    Definitely not collector’s items. The gameboy is the second best selling handheld of all time, if I’m not mistaken. Right after the DS. They’re still very common and inexpensive. Definitely not considered a collector’s item just yet.

  6. @john92
    thats why i said almost collectors items.
    maybe its different where you live but i didnt see a gameboy on sale for some years now no matter what the condition. on the other hand everyone is trying to get rid of their gba or even (broken) ds original/lite…

    thx for the clarification i can see the interest in that

  7. I wanted to connect my Game boy colour to my TV but haven’t done anything like this before. I don’t want to buy more than I have to and I was wondering if anyone could outline how it do this.


  8. Josh, in short you read the data as the fellow did to find the protocol and as he rebuilt on the computer you must process this with fpga/arm or something and gen a composite signal or even easier VGA with a dspic sure possible. Moo! yay for fullstops

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