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Project: Retro-Style Tablet Computer
Entry: 1 - Thoughts on Inputs
Category: {Electrical Engineering, Retro Tech}

I haven't had much time to devote to this project, and I doubt I'll
have much time till June. But I have been considering what types of
inputs I'd like the device to have. At the moment, I'm considering just
flat out copying the Alien: Isolation tablet design. Regardless, I want
to use some mechanical keys, thumbwheel potentiometers, rocker switches
and perhaps a slide potentiometer as well.

I've been reading up a little about producing my own firmware for the
inputs. My custom EC controller will either be built out of an EFM8
or STM8 microcontroller. I'm unsure how I want to connect the EC to a
larger MCU/SOC. The main system will initially be a raspberry pi or
raspberry pi clone, but my ultimate desire is to implement a RTOS on an
STM32 or just run a bare-metal program on that STM32.

USB HID would be easiest in the short run, but, to be frank, that just
doesn't sound like fun.

I'm deliberating which way to go for connecting the inputs to the EC.
Matrix or Charlieplexing. As it stands, I still have much to read on
these two approaches.

For the mechanical switches, I'm looking at using some type of Kailh
clicky switch, such as the Kailh Pro Light Green Switches. Overall,
they will have a ~16mm height to them, but if the main body of the
tablet is ~1.2-1.5cm, then they will be just fine. Besides, looking at
the Alien: Isolation tablet, tall keys look cool on the device. I am,
afterall, building something to look rugged and retro, so bulky is just
going to be a part of it.

My main goal at the moment is to work on a PCB for the mechanical keys
and get some simple keyboard firmware written for either the EFM8
or STM8. I already have an STM8L discovery board collecting dust at the
moment, so I guess STM8 it is.



#### Page Created: 2023-04-15 ############ Last Edited: 2023-04-15 ####