A500 Mini – part 8 – partly working keycaps and a small PCB reveal

First working keyboard keycaps are off the printer!
Only this bit to show as most of the print failed 😛

Well,, 3 prints failed, I’m trying to learn how to use my Photon Mono-X, so far mostly unsuccessfully, these were printed using a known good combination of Photon Mono and Commodore Brown resin 🙂 ….and still it partly failed!!

Next, I have to optimise the design for printing.
I’d added some features to make them work better, but, those features don’t translate to printing very well, D’oh! (That’s called not doing Design For Manufacture!).

Resin printing can be a hard beast to tame, especially when printing 94/98 individual items (98 if I can two keyboard types!!)

This first print is literally an ‘auto supports, Jab a few extras on, hope for the best’ quick test to prove the mechanics.
When the design is finished,
I’ll need to spend a couple of solid DAYS (maybe a weeks worth of evenings) adding thousands of supports MANUALLY to ensure every keycap comes off the print perfect!

That sounds a lot, but printing a single item is different than printing the same item hundreds of times, so it’s really worth the up front investment in time.

And, speaking of time, I’ve just clocked about 600 hours evenings and weekends, on this project now 😛

I’m rather happy otherwise, next week, I should have a full working keybaord to demonstrate 🙂

Another failure
Another failure!

And, the reveal, part 2

It’s here!!!!

A500Mini Keyboardification – Part 6 or 7 I think

Minor update on progress…made the schematic a bit clearer for me to understand, also am doing a dual footprint style setup – where I overlay multiple component footprints incase one becomes hard to get.

I’m also creating two ways of driving the matrix, an on-board RP2040 chip and, if they become hard to get, a seperate daughterboard which can house a Pi Pico

Kinda pausing PCB development until my Amiga 500 Mini device arrives in the post, but i’ll be playing with the PRK firmware next!

A500 Mini Keyboardification – Part Deux

Maybe a 2 part kit for the Amiga Mini?

Minor update! – Slowly working on the PCB design for the Amiga Mini – I’m tempted to actually produce a few of these as a Beta run so I can get ahead on the keyboard matrix programming.

I’ve priced up on https://jlcpcb.com/parts/ a BOM to build a minimalist Pi pico so that I can place one directly on the keyboard – and surprise, just like the Arduino Pro Micro device – The sum of the components is more expensive than the price of a full Pi Pico ! BUT, and key point, it’s not all that much more. building Arduinos out of components were typically around DOUBLE the cost. The Pi Pico isn’t!.

However, adding a RP2040 discreet chip to my PCB adds a small level of additional complexity to the board and puts me at risk of parts going out of stock so it’ll be a weigh up when the real Amiga mini is released – If there’s enough space on-board to make a 2 layer board, I may well do this. If not – well, that’s what the TWO circuit boards above are.

Early days yet, but first look suggests that the above would be only marginally cheaper (almost not worth it) than putting a discreet pi pico on-board

oh, and of course, these will be fully populated boards! just add keycaps and ‘go’

Brain surgery! RP2040 style (32u4 ft Raspberry pi Pico)

That’s a Pi Pico
Partying like it’s nineteen QWERTY nine!!

The interest in the mini keyboard is strong as ever, but – there’s a new kid on the block soon – The Amiga A500 Mini

That Beastie –

To turn this Mini’s ridiculously small keyboard into a ‘toothpicks required to operate’ WORKING keyboard will be tricky as it has a significantly larger number of keys than the C64Mini

Infact, there’s 96 on European Keyboards and 94 on others? ..Either way – it’s More than 81 – which is the maximum you can put on 9×9 Matrix – which exceeds the capacity of the good old 32U4 when used as a keyboard (well, technically, the Pro Micro I use has 20 GPIO available, Allowing for 100 keys IF I go and hack out the two LED’s and solder a bridge)

So…Enter the Fantastic (and new) Ruby Firmware for Keyboards – PRK,

Which can be found here –


and, with a good overview – here on Youtube (in Japanese, but, enable Captions and translate to English, you’ll get the gist of it)

It’s taken me a Solid Month to figure out how to get this far – I’m a relative noob to Linux, cross compilation, Ruby, C, and, generally ‘stuff’ like this –

To be able to compile this, i’ve setup WSL for Windows – which is essentially Ubuntu Linux, running nativley in Windows!

Inception! WSL running Ubuntu whilst i type this blog!

I’ve also had to setup the Raspberry Pi Pico-SDK

Ruby – For Linux – something higher than 2.6

Bundles for Ruby

And a few other things….all of which are quite finickitey and throw a wobbly at the slightest provocation! – Linux is fun eh!..

I’ll eventually get around to step-by step documenting and linking each step to ensure a good build environment so that others can duplicate what I’m doing

Once it’s all compiled, I drag the .uf2 file over to the pico (after holding bootsel whilst plugging it in) the thing reboots and becomes a keyboard

What’s Next………..

  • Ensure the Keymap is correct
  • Finish the basic keyboard layout, testing all basic keys
  • Introduce shifted keys
  • introduce ‘layers’ to ensure special keys are correct
  • introduce fancy stuff

Where this is going……………..The RP2040 Chip is fairly priced against the 32u4. I’m hoping that I can eventually switch the C64mini keyboard over to a fully SMT ready assembled kit – just add keycaps. And, i’m hoping I can do that for the Amiga Mini!, as much as I love soldering 600+ points, I appreciate some of you out there don’t!

And, I’ve another TOP SECRET project on the go also…It’ll blow yer mind! but, in 2022 that one, it’s a long burn that ‘looks’ finished (i’m holding it in my hands now!, all 2 circuit boards and about 100 3D printed pieces) but, needs quite a bit of work behind the scenes.

Also, Blinkenator, slow going, but I’m really trying, it’s just hard getting over this hurdle where it must be soldered….one last thing to try!

And, final before I go to bed, the C64 mini running the keybaord upgrade kit with pi Pico transplanted brains!

It’s being captured via a HDMI capture dongle and OBS studio so I can use my laptop as a test monitor!