A hobbyist replaced a failed monochrome STN display in an old Samsung cash register using a low-cost microcontroller instead of expensive parts.
Adapter boards that convert HDMI or VGA signals into DSI lanes for TFT panels are easy to find online, and boards that convert DSI back to HDMI exist too. These typically rely on dedicated silicon or, for a do-it-yourself build, an FPGA. In this case, though, the job was done with something much simpler, which shows that the right display can make the problem easier.
The project, documented by Voltage Ventures, involved a Samsung cash register that looks like it dates from the 1990s. Its defective display was a monochrome STN panel, and a replacement would have been expensive. The builder instead chose to translate the signal between the old panel and a newer one. The original display uses a 4-bit data bus, so the author sampled the bus and worked out the timing it used.
The display has a resolution of 320 by 240 pixels, which is modest by modern standards. Once the data format was understood, the signal was converted to monochrome VGA inside a microcontroller. The early version ran on an STM series chip, and the work was later moved to an RP2040, the chip used on the Raspberry Pi Pico.
Hackaday described the project as a reminder that even broken, old equipment can often be brought back into service.
Source: Hackaday
