Aaron Christophel's Aspire PIXO Vape Now Runs DOOM on Its Own Chip, on an Engine Built for a 32 KB Clamp Meter

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The first time Aaron Christophel got DOOM onto a vape, it was a cheat. His 2025 firmware for the Aspire PIXO turned the vape’s screen into a USB display, and a WebSerial page streamed DOOM to it from a computer. The README admits as much: “we can use a screen share cheat to hack DOOM onto the Vape.”

On October 22 he pushed the real thing. “The PY32F403 renders every frame itself, reads the map data from the 16 MB SPI flash and takes input from the touch panel. No PC involved,” the port’s README says.

The PIXO is “a ~30€ VAPE which got quite some power in terms of Computing hardware”: a Cortex-M4F at 144 MHz, 64 KB of RAM, 256 KB of flash and a 173 × 323 screen. Stock DOOM, per the README, “needs several megabytes.”

The engine that closes that gap is DMC100-Doom by Artur Bieniek, a DOOM for the FNIRSI DMC-100 clamp meter “with 32 KB of RAM.” Bieniek’s repo went up on October 19. Three days later it was running on a vape. Christophel’s README is blunt about the credit: “That port is the whole reason this is possible.”

The finished firmware takes 189 KB of the vape’s flash. It plays episode 1, and the proof isn’t a photo. The README says the player’s start position was read straight out of RAM: “(1056, −3616) facing 90°, which is E1M1’s player-1 start, exact to the unit.”

Each push now builds a release from scratch. VapeDOOM v0.1.3 ships the firmware, the flash image and a SHA256SUMS file. What nobody has published yet is a battery figure for a coil-powered handheld running DOOM.

Steal this

Guard every compile-time constant a build flag is supposed to override. When a header says #define RC_SETS 32 with no #ifndef around it, -DRC_SETS=256 loses without a word, and that’s exactly what kept this port’s cache eight times too small. It’s like a thermostat with a sticky note over the dial: you turn it, and the room never changes.
When a button press “sometimes” disappears, check every pin you OR into the read for a pull resistor. Here a floating pin, PC5, flickered mid-press, reset the debounce count, and swallowed the input. Kind of like a doorbell wired to a loose screw that rings, then doesn’t.
If one frame of your main loop can take more than 50 ms, feed the watchdog from a timer interrupt instead. This board has an external watchdog chip that yanks reset whenever PC6 goes quiet, so the port feeds it from SysTick at 1 kHz. A slow frame fed from the loop “would be a reset.”

Why it matters

The hardware fights you in ways you can only measure. The screen and the flash chip share one SPI bus and one data wire, so “while a frame goes out, no map data can be fetched, and the other way round.” The README calls the polled pixel pump “the shape of the hardware,” not a compromise.

The biggest speed-up was a bug, not an optimization. That unguarded RC_SETS define meant 4,770 flash reads per frame. Fixed, it dropped to 483, flash time fell from 57.8 ms to 9.6 ms, and the frame rate jumped from 11–15 to 19.8 fps. The screen is now the bottleneck, and at the bus’s 36 MHz maximum the README says “nothing more comes off without a faster bus.”

Glass is a worse controller than a switch. On the clamp meter, holding POWER walks from menu to quit prompt to power-off, which makes sense under a thumb. On a touch corner, “a finger left lying in the corner walks through all three without anyone’s help.” The fix sends one 150 ms press and nothing more until the finger lifts.

Throwaway electronics keep getting real computers. A vape with a Cortex-M4F, a megabytes-deep flash chip, Bluetooth and a color touchscreen is a dev board somebody decided to fill with liquid.

DOOM ports used to be about whether a chip could do it at all. This one hinged on somebody else’s engine landing three days earlier, ready to be ported again. The next device on somebody’s bench with 32 KB of RAM and a screen probably already qualifies. The open question is which one gets picked before the engine’s own author finishes his next round of fixes.

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