BlockBoy V3

A completely new PCB and smart LEGO cartridges

The V3 PCB has been rebuilt from the ground up. That was necessary to make room for the battery, which now sits directly on the PCB instead of inside the cartridge.

That allowed me to do something I had been working towards for a long time: keep the LEGO cartridges and make them functional.

The PCB carries a sensor that can measure magnetic fields. Hide a small magnet inside a LEGO cartridge and you can link a game to that magnet's field yourself. From then on the BlockBoy knows which game belongs to which LEGO cartridge: boot it up with that cartridge inserted and the matching game starts.

This is about the LEGO cartridges from the set. Real Game Boy cartridges are not supported.

Real-Time Clock (RTC)

The battery left a lot less room on the PCB, but I still managed to fit an RTC chip.

In-game times and time-based events are finally remembered correctly. Think day and night cycles, and events that only happen at a specific time.

USB-C audio solution

Finding a decent spot for a headphone jack gave me quite a headache. Every position I tried called for major modifications, and that was exactly what I wanted to avoid. In the end I found the solution in the USB-C port.

It was not simple. The BlockBoy runs on 3.7V (battery) or 3.3V, while USB audio officially expects 5V. I came up with several ways to get 5V out of the USB port, but none of them were stable enough. Just when I was about to give up, I found out that a large share of USB headphones simply work at 3.7V. That makes audio over USB-C possible after all.

USB audio is not detected automatically. You switch it on or off yourself in the menu.

The port itself has also been moved to the position of the EXT. CONNECTOR marking. That puts the connector exactly where you would expect a port on a Game Boy.

Buttons and battery indicator light

Buttons. Volume and brightness are now controlled by small lever switches that you flick up and down.

Battery light. The nostalgic red battery light is fully working:

• Softly lit while charging
• Bright when the battery is full
• Gradually dimming as the battery drains during play

The brick is supplied as a replacement, so you do not have to modify your original LEGO brick. Even the word "battery" is printed on it again.

Showcase Mode

In Showcase Mode the BlockBoy plays through your games automatically, as a showpiece on your desk. That was already possible. These features have now been added:

• You can put together a favourites list and have that play as the showcase
• A timer that works together with the RTC chip
• You can set how long a game plays before it moves on to the next one
• The loading screen between games has almost disappeared

Just like on the V2, you can add a USB-C connection at the back again. That routes the cable neatly out of sight instead of leaving it visible at the side, which is what you want when the BlockBoy is on display on your desk.

Wireless Link Mode

Playing Tetris against each other or trading Pokémon can now be done wirelessly, up to a distance of about 5 metres.

It does not work for every game yet, but that is being worked on. Updates are on the way.

SD card and WiFi network

Storage. The limit of 32GB and FAT32 is a thing of the past. Larger cards are now fully supported.

WiFi and network. Connecting to your WiFi network has become a lot more user friendly thanks to an on-screen keyboard. The connection is used to fetch the correct time and to reach your SD card through a browser within your own network. The card is still accessible over USB as well.

External Bluetooth controllers

Maybe a little redundant for a handheld. It started as a side project, but it worked, so I added it. You can now pair external controllers, as long as they support Bluetooth Low Energy (BLE). Not every controller does. The Xbox controller is one I know works, and in the video below I am using a Shanwan controller.

GBA emulator optimisation

Last but not least: the Game Boy Advance emulator. The ESP32-S3 is a powerful chip, but running GBA software was far too slow at first, and simply unplayable.

Over the past few months I have thoroughly reworked and optimised the code, with a lot of help from AI. After plenty of hours of programming and running benchmarks it finally worked out: the Pokémon games now run smoothly, apart from a few small frame drops. A number of smaller games run well too.