January 1, 2025
The Raspberry Pi 500 is an excellent idea for a combined Pi 5 and keyboard. There are limitations. I offer here the prototype of an alternative.
Who?
Who wants something other than the Pi 500? Anyone who types frequently has a preference for different keyboards. 85% size or 100% size instead of the Pi 500 60% keyboard. Cherry red or Cherry brown style keys. Large lettering. Trackpads. Numeric pads.
My preference is Cherry reds in an 85% TKL keyboard.
When?
You need a different keyboard when you have experienced a keyboard better for your use when compared to the keyboard in the Pi 500. There is no going back to a slower more difficult keyboard.
If your previous experience is the regular Raspberry Pi keyboard, you will miss the better printing on the keytops and the built in USB 2 hub. When you have to type an 1,100 page text book, the short keyboard movement on the Pi 500 does not help. When you type in low light levels, there is no backlight.
When you have a box of spare NVMe SSDs left over from upgrades, you miss the Pi 5 option of a PCIe interface.
Where?
The Pi 500 has thinner print on the keycaps when compared to their regular keyboard, making reading the keys difficult in anything other than the strongest light. There is a need for better print and back lighting for lots of workplaces. You cannot read the keys in the subdued lighting next to a stage.
The Pi 500 is compact, a notebook style 60% width, which slows down typing in any commercial workplace. 85% and 100% keyboards are a better fit. The larger keyboards work better for all sorts of editing and games.
The Pi 500 does not have the PCIe NVMe SSD option of the Pi 5 for storing large files fast, eliminating the Pi 500 where you need to handle lots of photographs and other large files. If made with a variation of the Pi 500 motherboard, my prototype with a wider keyboard could fit an NVMe disk or two. There would be room for a PCIe adaptor plate and some of them handle two NVMe disks at PCIe 3 speed.
The Pi 500 motherboard has a place set for a PCIe socket and an NVMe up to 2280 length but the SSD faces up to the metal heatsink and would compete for cooling when the machine is working hard. Plus you cannot replace the SSD without wrenching the machine open and the heatsink off.
Why?
The Pi 5 offers a wide range of choices. The Pi 500 blocks the options of most interest to me and many other Pi 5 users. If the Pi 500 motherboard was unlocked from the Pi 500 keyboard, the Pi 500 motherboard would be fitted to other keyboards to give us a better choice of keyboards.
A larger format keyboard would open up space for adaptor plates plugged into the Pi 5 PCIe socket. The Pi 500 motherboard has the outline of a PCIe socket. If the outline was populated, a wider keyboard, an 85% or 100% keyboard, could squeeze in a plate for a one or two slot PCIe adaptor.
Way?
I had a spare 100% keyboard with an unused numeric keypad and some keys breaking down. I removed the numeric keyboard, inserted a Pi 5, and tested the combination. It worked well but the result is still a big lump.
The prototype would fit together better if the Pi 5 was formatted like the Pi 500 with all the ports along one edge. I could then use my favourite form of keyboard, the smaller 85% or TKL keyboard.
Worth?
The extra space in a wider keyboard is enough to fit all the features of a Pi 5. Well, all the ones I use. I do not add HATs on top as they do not do anything I need and HATs make the Pi 5 to big for ready made enclosures.
The extra width would fit a PCIe adaptor plate with the slots facing down where you could access the slots through a pop out panel. A two slot adaptor would fit almost everything I add on. The other benefit of a wider keyboard would be the space for a USB 2 style hub similar to the one in the regular Pi keyboard. You could then plug in a mouse, a graphics tablet, and a USB memory stick.
The best USB memory sticks tend to be USB 3. You can plug a USB 3 stick into one of the USB 3 sockets then a backup disk into the other USB 3 socket, leaving one USB 2 socket for the mouse and nothing for a graphics tablet or your smartphone or your camera. The three USB 2 sockets on the back of the regular Pi keyboard would be a big help.
What?
I had a spare 100% keyboard with a key that started to fail. Ideal for my experiment as I could damage the keyboard then throw it out. I opened the case, unsoldered the keys in the numeric pad, and mounted the Pi 5.
The board had a top case, a bottom case, a circuit board, and a metal frame. I left the metal frame untouched to save time by not cutting the metal. That left the Pi 5 bulging out the top at least 5 mm higher than needed. Plus it meant mounting the Pi 5 in a less than ideal position. If I cut the metal, the Pi 5 would mount down with the top of the rear sockets in line with the top of the keys.
The metal plate provides rigidity. Cutting the plate would reduce the strength. Cutting the Pi 5 into the plate would also create problems fitting plugs into the Pi 5 socket. Starting with a Pi 5 laid out like the Pi 500 motherboard would simplify the design of a keyboard to fit the Pi board.
One of my other keyboards, an 85% with a solid metal plate, would be a better fit as the solid metal plate could be the heatsink for the Pi 500 motherboard. One less part for the combined product.
The connection of the keyboard to the Pi board is another problem. My experiment used a keyboard with a socket that is not USB 2. I would have to cut the cable to make a short cable from they keyboard to the Pi. There are flat USB cables which would be a better fit if you were planning to match they keyboard to a Pi. The keyboard motherboard could be manufactured with the flat socket and the keyboard cable could have the matching flat socket at no difference in cost. The whole project could be easier of the Pi 500 motherboard adopted one of the simpler flat cable interfaces.
I have not measured the exact length available. The Pi 500 appears to have a 250 mm board. My TKL keyboard has room for a 340 mm board. My PCIe adaptor board for the Pi 5 is 90 mm. The Pi 500 motherboard and the PCIe adaptor board should squeeze in to an 85% TKL keyboard.
Here is my prototype:
Comments