Overview
The company had signed a contract to fit access control at 30 new sites over six months, and decided to build its own controller rather than buy one. I wrote the firmware: a Raspberry Pi talking to Arduinos, which read RFID cards over Wiegand. The controller passes each card to the edge computer already on site, which checks the person’s access group.
It worked well enough that larger sites started asking for their high-traffic lanes to be ripped out and replaced with it, in place of the established access control boards they already had.
The challenge
Nobody at the company had built an access controller before. This was its first hardware product, and the deadline was fixed by the contract.
The solution
I designed the controller around the edge computer the company already ran, so card checks stayed fast and reliable without new back-end infrastructure. The firmware was built to be extended, which meant later sites with their own quirks could be added without rework.