Translating An Old Display To A New One

A recent project illustrates how to replace an old STN display in a Samsung cash register using a Raspberry Pi Pico. This innovative approach highlights the capability of modern technology to breathe new life into outdated devices.

A quick search through AliExpress reveals various PCBs that convert HDMI or VGA signals to DSI lanes for TFT panels. Some boards even translate DSI to HDMI. While many of these solutions require dedicated silicon or an FPGA, the project shows that simpler methods can work effectively.

The original display, a monochrome STN unit, is part of a cash register that appears to be from the 1990s. Given the high cost of a replacement, the project aimed to find a cost-effective solution for translating signals between the old and new displays. The STN display features a 4-bit data bus, and the team documented how they sampled this bus and identified the necessary timing.

Despite its low resolution of 320 by 240 pixels, the display’s format was successfully transposed to monochrome VGA using a microcontroller. Initial development utilized an STM series chip before transitioning to the RP2040 for better performance.

This project serves as a reminder that even outdated technology can be salvaged and repurposed with the right tools and creativity.

Source: Hackaday