monic part 3: towards a handheld
07-01-2020, 01:54 AM (This post was last modified: 12-09-2020 01:41 AM by F-73P.)
Post: #1
 F-73P Junior Member Posts: 18 Joined: May 2020
monic part 3: towards a handheld
Previous: monic part 2: connecting the keypad

I will now place the display and matrix keypad on veroboard. The calculator can then be connected to a development board (such as the NXP i.MX RT1010 I have been using so far) via terminal blocks on the left of the veroboard.

I am also trying to find keycaps for the Omron B3F-1052 pushbuttons; any suggestions?
07-01-2020, 10:17 AM
Post: #2
 Maximilian Hohmann Senior Member Posts: 865 Joined: Dec 2013
RE: monic part 3: towards a handheld
Hello!

Very interesting project, looking forward to see more of it.

(07-01-2020 01:54 AM)F-73P Wrote:  I am also trying to find keycaps for the Omron B3F-1052 pushbuttons; any suggestions?

I have used this kind for some tinkering projects in the past (this is an eBay-link, unfortunately I couldn't find them anywhere else - they come from China anyway, no matter who you order them from):

https://www.ebay.com/itm/A14-Tactile-Cap...3216076402

You can select a keycap in the colour you like and snap a transparent cover over it. The gap between keycap and cover is large enough for a key label printed on solid/thick paper. These caps should also fit your Omron switches, but better compare the measurements.

Regards
Max

NB: Maybe I missed it in your earlier posts, but what does "monic" stand for?
07-23-2020, 04:02 AM
Post: #3
 Garth Wilson Senior Member Posts: 444 Joined: Dec 2013
RE: monic part 3: towards a handheld
(07-01-2020 01:54 AM)F-73P Wrote:  I am also trying to find keycaps for the Omron B3F-1052 pushbuttons; any suggestions?

We use them in a couple of our products at work. Availability has never been a problem at all. See https://www.mouser.com/Electromechanical...ps&FS=True

07-28-2020, 09:21 PM (This post was last modified: 07-28-2020 09:25 PM by Chr Yoko.)
Post: #4
 Chr Yoko Member Posts: 55 Joined: May 2020
RE: monic part 3: towards a handheld
Very nice project !
Your chosen microcontroller looks very powerfull , why such choice instead of a 32bits Arduino such as a STM32 base ?

Hereby EEVblog that is showing how to get made a custom membrane keyboard :
From here :
(exemple @ about US$255 for 4 parts, with embossed keys , their stainless domes and 4 colors on the overlay) OK, bit expensive and not as good as a real keyboard, but has a professionnal look to it. Also I would be interrested by the software side of your project ;-) 08-01-2020, 05:58 AM (This post was last modified: 12-27-2020 03:37 AM by F-73P.) Post: #5  F-73P Junior Member Posts: 18 Joined: May 2020 RE: monic part 3: towards a handheld Thanks for the suggestions. I have ordered Omron and Alps Alpine switches and keycaps, and have started making some keypad labels: (07-28-2020 09:21 PM)Chr Yoko Wrote: Also I would be interrested by the software side of your project ;-) See here for firmware for a programmable scientific calculator. After the handheld is built I will focus on adding support for arbitrary-precision rational and floating-point arithmetic. (07-28-2020 09:21 PM)Chr Yoko Wrote: Your chosen microcontroller looks very powerfull , why such choice instead of a 32bits Arduino such as a STM32 base ? The i.MX RT EVK boards offer speed and large memories, and the IDE is free and supports programming in C and assembly. (07-28-2020 09:21 PM)Chr Yoko Wrote: Hereby EEVblog that is showing how to get made a custom membrane keyboard : https://www.youtube.com/watch?v=H8XBBfvsPj0 From here : https://www.jrpanel.com/switch/buy/ (exemple @ about US$255 for 4 parts, with embossed keys , their stainless domes and 4 colors on the overlay)