The Raspberry Pi 3 may not be the latest and greatest Raspberry Pi, but at one time it was and it made its way into many projects including the TPCast-VR, a wireless adapter for VR headsets such as Occulus Rift and HTC Vive. These custom Raspberry Pi 3 powered boards are now available to buy separately, as spotted by CNX Software. This custom board is known as the Raspberry Pi 3 Mini.
What you get is a Broadcom BCM2837 SoC featuring a quad-core Cortex-A53 processor running at 1.2GHz with Videocore IV GPU and 1GB of RAM. And while there are no USB ports, HDMI, or wireless interfaces, you do get a four-pin AV port for composite video and stereo sound, two USB 2 interfaces via a J12 header, a Micro SD slot and the CSI camera interface. There is no micro USB port for power, instead 5V and GND is provided via the GPIO, so the VR headset it connects to must have some form of voltage regulation. Speaking of the the GPIO, here we see a compromise. Instead of the familiar 40 pins we see a 28-pin GPIO so HAT compatibility depends on whether the board uses pins beyond 28. The board measures 2 x 2 inches (5 x 5cm) and as you can already guess, does not follow the layout of a conventional Raspberry Pi board.
Custom Raspberry Pi boards are not new, in fact the service started way back in 2015 via Element 14. Customers purchasing over 3000 Raspberry Pis would have access to engineers who would tailor Raspberry Pi to the customer’s needs. We’ve reached out to Element 14 for current information on the service, as existing URLs redirect to the Element 14 Raspberry Pi page.
The bare board is available from FatboyPV for $24.99, while a kit with an additional adapter board, cables, fan, and a plastic enclosure is on AliExpress for $55, or on its own for $33.25. A Raspberry Pi 3 barebones kit can be had from Amazon.com for $49.99, so you’d need a very good reason to want this particular board.
It has gained some traction, however, in the drone-flying community, where it acts as a more powerful alternative to the Raspberry Pi Zero in first person view streaming camera rigs running the OpenHD open-source platform, which is exactly what the AliExpress kit is targeting.