The development blog of gotnull. Low-level firmware, fantasy consoles, games, and whatever else I am building.https://blog.gotnull.com/en-ushttps://blog.gotnull.com/i-keep-choosing-hard-mode/https://blog.gotnull.com/i-keep-choosing-hard-mode/I had a working HDMI path at 12:48 in the morning. Then at 10am, well rested and full of hope, I picked up the tiny SPI screen instead and spent nine hours reinventing flicker. A note on patience, and on why hardware scanout is the thing I should have just waited for.Mon, 29 Jun 2026 00:00:00 GMTrusty-nailfirmwaredisplayshdmistm32https://blog.gotnull.com/the-spi-panel-saga/https://blog.gotnull.com/the-spi-panel-saga/Getting the desktop off the USB stream and onto a real LCD. A dead-end controller that latches on the wrong clock edge, a switch to the ST7735, and climbing from 1 MHz to 25 MHz without losing the audio.Sat, 27 Jun 2026 00:00:00 GMTrusty-nailfirmwaredisplaysstm32https://blog.gotnull.com/getting-sound-out-of-it/https://blog.gotnull.com/getting-sound-out-of-it/An I2S DAC, SAI plus DMA, and three gotchas that each ate a session: a mute pin nobody pulls high, a data cache fighting the DMA, and an async executor that starved the audio to silence.Sun, 21 Jun 2026 00:00:00 GMTrusty-nailaudiofirmwarestm32https://blog.gotnull.com/real-pico8-lua-on-a-cortex-m7/https://blog.gotnull.com/real-pico8-lua-on-a-cortex-m7/Vendoring Lua 5.4 into a bare-metal firmware, the 64-bit integer bug that printed 42 minus two-to-the-32, and why a hardware watchdog beat an instruction-count hook for stopping runaway carts.Tue, 16 Jun 2026 00:00:00 GMTrusty-nailluafirmwarepico-8https://blog.gotnull.com/a-fantasy-console-on-a-dev-board/https://blog.gotnull.com/a-fantasy-console-on-a-dev-board/Rusty Nail is a windowed pixel-desktop OS running bare-metal on a Nucleo-H753ZI. How it is put together, and why the display layer is an abstraction from day one.Thu, 11 Jun 2026 00:00:00 GMTrusty-nailfirmwarerustarchitecturehttps://blog.gotnull.com/starting-this-blog/https://blog.gotnull.com/starting-this-blog/A place to write up the things I build, mostly low-level. Short note on why it exists.Sun, 07 Jun 2026 00:00:00 GMTmeta