Tag: hdmi

I spent days optimising the HDMI coprocessor because every symptom said it was holding the SNES back. The optimisations worked, the frame rate climbed, and then the measurements turned around and convicted a different part entirely: the wire. This is the story of proving a bottleneck before building its replacement.

I soldered two bodge wires, taught the HDMI coprocessor to talk back, and made it run the SNES sound chip with real Super Mario World music. It reached 97% of realtime. That number is worth more than a pass.

I put a Mega Drive emulator on a 480MHz Cortex-M7, carried its video over an 8MHz jumper-wire link, and got perfect music beside a screen that tore in half. The fix was to make a slow frame arrive atomically.

Two days building the console's v2 shell: a SPLORE-souled library, a crash hunt that ended eight kilobytes from a stack floor, and PICO-8's hidden palette arriving over an 8-bit wire.

Two days from a feasibility study to DMG code rendering pixel-perfect on the TV: picking an emulator core, passing Blargg and dmg-acid2 on the host, and teaching the console's SPI video wire to carry two frame geometries at once.

The HDMI picture was pixel-perfect and still looked soft. Fixing that took one good idea (a 3x full-resolution palette scanout) and one long afternoon of being framed by a heap that only sometimes existed.

The eight little wires into the HDMI connector were the one part of the board I'd decided to hand off. A script almost did it, then made it worse. The right tool did.

Getting real console frames from the H7 to the Feather RP2040 DVI took two days and five separate root causes: a CPU-starving encoder, a FIFO race, a missing ground return, a clock divider that lied to me, and a GPIO port that mutes my DAC.

The Feather RP2040 DVI arrived this morning and had the console's palette on a monitor within 45 minutes of hitting the bench - after a wrong-variant pinout diagram, a factory firmware with no drive, and a 3D printer slicer typing G-code into my REPL.

I bought a 50-pin RGB888-to-HDMI board for the fantasy console, then counted the pins. Two of them are Ethernet, three are the audio bus, and the Nucleo never had 24 to give. The fix might be a second microcontroller whose whole job is HDMI.

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.