Samsung printer’s control panel hacking

Reverse engineering of a Samsung printer’s control panel.



My father picked up a dead Samsung SCX-4521F printer/scanner combo, we made a complete teardown (a great way to learn things and gather parts 👌). I collected the control panel, which has a 1602 LCD display with no backlight and quite a few buttons and LEDs.

Samsung SCX-4521F

I started to look at controlling the panel from the connector, but as the rest of the printer’s electronics was already trashed, it was quite hard to do something with it (HT48R50A-1 microcontroller, could probably be reprogrammed with the proper tools and some patience). So I started analyzing the PCB traces to map the multiplexed matrix of the buttons, it took quite some time but in the end I was able to solder everything onto my Arduino Nano. I was then able to get the status of each button and also control the LCD and LEDs, so the control panel can now be repurposed for another project. 🙂

The single layer PCB, color-coded to analyze the matrix

The code is nothing special so I’m not going to publish it in a repo, it’s just some multiplexing and a simplified version of my IntelliCasier’s event system.