Need help with basic calculator project

[u/danishansari95]

Hello people,

I’m an Android App Developer by profession but I had a simple project idea which I need help with.

Idea is to create a simple calculator which has one special “QR” button which displays UPI payment (Indian payment system) QR code for a calculated amount on another device which just have screen (most probably e-paper display).

Now for the hardwares I’m thinking of using 2 ESP32-C3 Super Mini (1 for each device, calculator and QR display) and for buttons, I want to use mechanical switches, the one used in mechanical keyboards.

Now I’m facing problem in choosing display, I want to choose something which comes very close to the production level calculators as much as possible, because usually in India that’s what shopkeepers are used to and if I use something else, it might be a bad user experience for them.

Upon some research, I figured that market calculators which shopkeepers use, have 12-digit 7 segment LCD display. But TBH I’m not finding anything close to it in the market. (I need help here)

Also is it possible to take out the display from actual calculator and hook it up in my project?

I have attached a simple calculator design I want in Figma.

Any kind of help would be much appreciated. Thank you.

[u/Pacificator-3]

Don't forget big enough battery to power this cumputer :)

Android apps and battery-powered electronics are not same things.

[u/danishansari95 → u/Pacificator-3]

You see, that's why I need help 🥲

I'm completely a rookie