A quick search through AliExpress will find PCBs that take HDMI or VGA and translate them to DSI tracks for TFT panels, and even boards that translate DSI to HDMI in the other direction. Usually they need dedicated silicon or if you do it yourself, an FPGA, but depending on the display this need not be the case. As an example, [Voltage Ventures] replaced a faulty STN display with a more modern one that uses nothing more complex than a Raspberry Pi Pico.
The display comes as part of a Samsung cash register that looks like it’s from the 1990s, which equates to a monochrome STN display. A replacement will cost a fortune, so some way to translate between the two was in order. It has a 4-bit data bus, so there is a description of how they checked the bus and identified the timing. It’s hardly the highest resolution display by today’s standards, a measly 320 by 240 pixels. Once the format is known, it’s a case of transposing it to monochrome VGA in the microcontroller. First work was done with an STM series chip, later this was moved to the RP2040.
We like this project, and it is a reminder that even something broken and old can still be saved.