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I built the Loyalty Card Emulator 🪄
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this post was submitted on 23 Sep 2023
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Privacy
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I use Catima, an Android app that never even connects to the internet. A dozen barcode types, optional card pictures, ZIP export/import etc. LCDs & OLEDs don’t work with laser scanners (those that project a sweeping line) but most shops have camera-based ones anyway.
Yep Catima is great and gets frequent updates
I was not aware of this app. Thanks for mentioning it!
I was wondering what the issue was, but laser always was the common denominator. Never even thought of that
The reason is that laser scanners use a rotating mirror or lens in front of the laser to create the scanline, and only have a single light cell, detecting rapid changes in red light intensity. They can’t tell where light is coming from so you could trick them into reading a barcode transmitted as a sequence of light pulses from a single source (like an optical mouse’s LED controlled by an Arduino) but not an array of light sources (aka pixels) unless they have different reflectivity as the laser scans across them (such as E-ink). Technically, reflective LCDs could work with laser scanners but transferring the code to a TI-83 calculator is not worth the effort.