# The GB Interceptor reads the cartridge bus and turns a Game Boy into a webcam

> GB Interceptor is an open hardware and open source adapter that uses an rp2040 to capture what the Game Boy sends over the cartridge bus, renders it and presents it as a USB video class device. It suits someone who wants to record or stream Game Boy footage, and it involves soldering and ordering PCBs.

**Staacks/gbinterceptor** — Capture or stream Game Boy gameplay footage via USB without modifying the Game Boy.

- Repository: https://github.com/Staacks/gbinterceptor
- Stars: 542 · Forks: 35
- Language: C
- License: not declared
- Published: 2026-10-22 · Updated: 2026-10-22 · Language: en
- Canonical page: https://hysenlabs.com/projects/staacks-gbinterceptor

## It taps the cartridge bus instead of the video output

The concept is the whole reason this device exists, and the documentation states it in one sentence. GB Interceptor is an open source and open hardware Game Boy adapter that uses an rp2040 to capture the communication on the cartridge bus, and that data is fed into an emulator, rendered, and then offered as a USB video class device. The distinction matters. A Game Boy has no video output of any kind, so capturing it the ordinary way is impossible without opening the console and tapping the LCD or the display lines. Reading the cartridge bus instead means the adapter sees the commands the Game Boy issues to the cartridge, which the same software knows how to emulate, because it is the same information an emulator already acts on. The rendering step then reconstructs the picture from those commands. The trade-off is inherent to the approach: the picture is reconstructed rather than captured, so anything the reconstruction does not model is missing, which is why the project keeps compatibility tables and why some rare things cannot work based on the principle of this device.

## There is no buy-it-now path, only a build guide

The project is not a product, and the documentation is direct about that. There is an order and build video to guide you through the build process, which the author highly recommends especially if you are not used to ordering PCBs, and a written build guide in the repository's wiki. The repository root shows what you are working with: a `case/` directory, a `firmware/` directory and a `pcb/` directory, which correspond to the 3D printed case, the firmware source and the PCB layout. The conceptual background is documented separately at there.oughta.be, with a page describing the capture cartridge concept, and an overview video is embedded in the readme. The author's own support guidance is worth reading before you start, since it sets expectations. For difficulties with ordering, building or using the device, the documentation asks you not to contact the author directly but to use the r/thereoughtabe subreddit, so that the answer can help others too. For bugs, and in particular for glitches in a game, the ask is to check the compatibility lists in the wiki first to see whether it is a known problem, and to open an issue otherwise.

## Firmware updates are a uf2 file dragged onto a USB stick

The update path is unusually simple, which is the result of the rp2040 bootrom rather than a custom installer. The [Flash] button, near the center and usually inside the case, is used only to flash a new firmware version. You hold it while plugging in the USB cable, the Interceptor appears as a storage device like a USB stick, and you drag the new firmware file, a uf2 file, onto it. Most users are told to install the latest release uf2 as described in the build guide. If you do want to build the firmware yourself, the documentation says you need the Raspberry Pi Pico SDK and to set PICO_SDK_PATH accordingly. Two further build details are called out: check out the submodules too, and make sure the TinyUSB submodule is at least on version 0.14.0, because the Pico SDK currently references an older version. The release history shows how little churn there has been, with v1.2.0 bringing MJPEG, 60fps and Apple compatibility on 2023-08-05, v1.2.1 described as a minor sign of life on 2026-03-23, and v1.2.2 on 2026-06-06.

## Plug it in, power it first, and it appears as a webcam

The usage section is short, and one step in it is the one people get wrong. You plug the Interceptor into your Game Boy and the Game into the Interceptor, connect the Interceptor to your computer, and only then turn on the Game Boy. It should show up as a webcam in any software that supports USB video devices, for example OBS Studio. You do not need to open the video stream first. The important step, as the documentation puts it, is that the Interceptor is powered via USB before the Game Boy is turned on. After that you turn on the Game Boy and play. Two physical controls sit on the board. The [Mode] button next to the LEDs switches between grayscale and green colours and toggles frame blending, with each press switching colours and frame blending toggled each time the button returns to grayscale. The [Flash] button near the center is only for firmware. The LEDs are a status channel: the red one indicates that the Interceptor is powered, and the blue one stays on as long as the device is in sync with the game, though it may briefly turn off for a fraction of a second when the Game Boy turns its display off, for example when loading a level.

## Lag is the acknowledged limitation, and the documentation says so first

The warnings section is the first substantive thing in the readme, and its first sentence is an instruction to understand what the device does and what its limitations are. Most importantly, as it says, there is a little lag which will make it unsuitable for playing on a big screen. It might be fine for slow games, but its focus is on recording and streaming. That framing is worth respecting. The device reconstructs frames from bus traffic, so the picture arrives after the moment it happened, and a device that adds latency between your input and the picture is a capture tool, not a capture card that substitutes for a console. If your goal is to stream a Game Boy to a large screen and play on it, this is the wrong device and no firmware update will change that. If your goal is to produce footage, a recording, a video for a channel, a clip for social media, the latency does not matter at all, and the compatibility notes become the thing to read instead.

## Not all software handles the video format, and not all games work

The second warning is about the edges of the format itself. In principle this is a USB video class device and does not require drivers, but not all software supports the unusual video format of the Interceptor. The documentation makes the same point in the usage section, that some software is not entirely happy with the exotic format even though it should work in most cases. Games follow a similar pattern: they should usually work, but sometimes there are details the Interceptor does not yet support properly, and some rare things cannot work based on the principle of this device. The project responds with three separate compatibility tables in its wiki, one for Game Boy compatibility, one for host software compatibility, for example OBS, and one for game compatibility. Reading all three before you commit is the single most useful step in evaluating this project, because they turn an open-ended risk into a list you can check against your own software and your own cartridges.

## The licence splits the code from the hardware design

The licence section is where the repository metadata and the readme differ, and the readme is the one with detail. The metadata records no recognised licence, but the documentation states that the code is released under the GNU General Public Licence 3 and that the design files, meaning the PCB layout and the 3D printed case, are released under the Creative Commons licence CC-BY 4.0. That split is a deliberate and common pattern for hardware-adjacent projects: the software carries copyleft obligations, while the physical design files are shared under attribution so that anyone can build their own board. For someone who wants to make one, that is an open invitation. For someone who wants to sell one, the copyleft on the firmware is a real constraint to read carefully rather than assume away, and the CC-BY 4.0 file still requires attribution to the original design. The project also accepts pull requests, bug reports and contributions of new case designs, and a new case design is the kind of contribution this project can use.

## How this compares to a video capture card and to a screen recording

Two alternatives frame the decision, and neither is the same project. The first is a conventional capture card: a device that takes the console's video output and passes it through as a standard HDMI or composite signal. The difference in approach is that a capture card reproduces the picture exactly, pixel for pixel, including any artefact the LCD produces, at the cost of requiring a video output to exist, which on a Game Boy means opening the console and soldering to the display lines, and modifying the hardware the GB Interceptor explicitly avoids. The second alternative is to record the gameplay the ordinary way, with a camera pointed at the console or a screen recording of an emulator. That approach needs no hardware at all and captures the real output, but the picture quality is bounded by the camera and the screen, and you cannot get a clean digital signal. The Interceptor sits between them. It gives you a clean digital capture with no console modification, at the price of a reconstructed picture, a small amount of latency, and a build that takes patience.

## Conclusion

GB Interceptor is worth building if you want to record or stream Game Boy footage without modifying the console, because the device reads the cartridge bus rather than the video output, and the result appears as a webcam in any software that handles USB video devices. It is a poor fit for playing on a large screen, since the documentation states plainly that there is a little lag which makes it unsuitable for that and that its focus is on recording and streaming, and a poor fit if you are not comfortable ordering PCBs and soldering, because the project routes you to a build video and a written build guide rather than a purchasable device. Before you order parts, read the three compatibility tables in the wiki, because not all host software handles the unusual video format and some games have details the device does not yet support, and note that the code is under the GNU General Public Licence 3 with the design files under CC-BY 4.0, while the last push to the repository was on 2026-06-06 with release v1.2.2 the same day.

## FAQ

### What does the GB Interceptor do and how does it work?

It is an open hardware and open source Game Boy adapter that uses an rp2040 to capture the communication on the cartridge bus. That data is fed into an emulator, rendered, and then offered to the host as a USB video class device, so the Game Boy itself is not modified.

### Can I play on a big screen with the GB Interceptor?

The documentation warns that there is a little lag which will make it unsuitable for playing on a big screen, while noting that it might be fine for slow games. Its focus is on recording and streaming rather than on replacing the console's own display.

### How do I update the GB Interceptor firmware?

Hold the Flash button while plugging in the USB cable. The device appears as a storage device like a USB stick, and you drag the new firmware file, a uf2 file, onto it. Most users install the latest release uf2 as described in the wiki build guide.

### What licence is the GB Interceptor released under?

The code is released under the GNU General Public Licence 3, and the design files, the PCB layout and the 3D printed case, are released under the Creative Commons licence CC-BY 4.0. The repository metadata itself records no recognised licence.

## Sources

- [Issues](https://github.com/Staacks/gbinterceptor/issues)
- [README](https://github.com/Staacks/gbinterceptor/blob/main/README.md)
- [Releases](https://github.com/Staacks/gbinterceptor/releases)
- [Staacks/gbinterceptor on GitHub](https://github.com/Staacks/gbinterceptor)

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Hysen Labs editorial analysis, written from the project's own repository and release notes. Cite the canonical page: https://hysenlabs.com/projects/staacks-gbinterceptor