Making a video card

A project log for Twitter feed on an old LED marquee

An adventure in '80s electronics and embedded Linux

Enrico GueliEnrico Gueli 05/23/2022 at 20:150 Comments

I decided I won't let the Linux machine control the display directly, not yet. For a few reasons:

Therefore, I'll let a separate MCU do the LED handling for now. I'll use an FRDM-KL25Z development board by Freescale:

I decided to use that instead of a traditional Arduino because I want to learn more about the ARM Cortex architecture, FreeRTOS, and other tools in "professional" embedded development.

The plan is to use this MCU as a "video card" that will directly control the row and column drivers. It will use one of its SPI peripherals as a master to control the column drivers, and the other as a SPI slave to get bitmap data from Linux. I'll then write a kernel driver that sends the right data to the MCU; maybe by also emulating a framebuffer device.