Cherry Pi


A Raspberry Pi mounted in a Cherry keyboard

Created: 8th April 2016


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Cherry Pi





Introduction

Inspired by the 'RaspCherry Pi', I wanted a more convenient way of using my Raspberry Pi computer. As a fan of BBCs and Amigas (which have all in one designs), I thought I'd have a go at building something similar, which meets my own requirements.

This page just shows off what I've done. It isn't intended as a how-to. Most of this project was put together by cutting bits out, gluing bits in, and seeing if it fits. Quite a bit of trial and error was used, along with a Dremel, and a hot glue gun.

The complete system, turned off

The Keyboard

The keyboard is a Cherry G80-3000, with Cherry MX Blue key switches. These switches are nice to type on, and have a nice positive click. The keyboard itself is built in a cheap and quite flimsy way. This accounts for the price, as it is one of the cheaper mechanical keyboards you can buy. This is an advantage to me as it means it is easy to chop pieces out to make the Pi fit.

Placing the components

The first stage was to place all the components on the keyboard's base plate. I decided what needed to go where, and either drilled or cut out holes. Part of the plastic needed to be removed to make the Pi fit in place. The HDMI port remains on the Pi, and all the other ports are extended, with header connectors added where possible.

I wanted all the ports, including the SD card to be usable (unlike in the project linked to above). The following photo shows the Pi and some of the extender cables in place, with some assorted headers added to the circuit board in place of the original connectors.

The connectors on the back panel are all standard ones available from suppliers such as Rapid Electronics. The only other connector is the Ethernet connector which I removed from the Pi, and glued onto the base plate.

The project as a work in progress.

USB Connections

It is worth noting how I did the USB connections. The Pi has 2 USB ports. One of these is used for the keyboard. The keyboard PCB is wired directly to one of the newly installed USB headers on the Pi. The other USB header is connected to a USB type A port, which is glued into the back panel. This facilitates the connection of a mouse or similar device.

I also wanted to be able to use the keyboard as a normal PC keyboard. Therefore, before reaching the Pi, the keyboard's signals/power pass through two switches. These physically disconnect all four USB wires from the Pi, and pass them through to a USB type B connector on the back panel. This allows the keyboard to be connected to a PC and used as a standalone keyboard.

If you are wondering why I used these two switches, its because I had them in stock.

The USB Keyboard connection detail

Audio and Video Connections

Basically, I used some screened cable to connect the panel mounting RCA and Headphone jacks to the Pi board.

Ethernet

I extended the Ethernet port out by using a small piece of ribbon cable, some fudged header connectors, and plenty of hot glue. There was a possibility that this might not work, but it worked fine when I tested it.

The new Ethernet connection

Power and SD Card

I've never seen the point in these USB power supplies. I have a nice benchtop 5V supply from which I power most things, so I attached a panel mounting barrel jack to the case, and used some nice thick wire to carry the power to the Pi board. The wires are connected as shown in the photo.

It was important that the SD card could be accessed easily, without opening the case. This is so the OS and software etc can easily be changed. Removing the SD card socket from the Pi was a bit tricky. It might be better getting a better SD card socket if possible, rather than using the Pi's. I cut a slot in the back for the SD card, soldered some ribbon cable on, and glued it in place.

Power and SD card sockets

Power and SD card wiring

GPIO

The GPIO port is just a standard piece of ribbon cable with standard IDC male and females headers added. The connector is glued onto the back panel.

The Finished Project

Putting it back together:

Nearly done

Left:

Left

Centre:

Centre

Right:

Right

Far Right:

Far Right

Finished Back Panel:

Back Panel

Back Panel

It Works!

Here is the finished project, running RISC OS.

Finished


Cool websites I recommend you should check out:

ClassicAmiga - Your Guide to everything Amiga

Amiga Computing and Retro Gaming

Link to Dave Jones EEVBlog

Electronics Video Blog

Electronics, Solar Power and Metrology

Old-School Game Blog

Other links:

The Aussie Space Time Traveller

E-Maculation - Macintosh Emulation

EEWeb - Electrical Engineering Community