flint

Firmware for the M5Stack Cardputer ADV. Eight apps: a drum machine, a breathing coach, and six views over coral, bankr, glyphbots, voxels and gwei.

ryanio.github.io/cardputer has the screenshots and how to run it without hardware.

View	Source	Shows
Reef	coral	The daily Coral Score guessing round
Bankr	bankr	Agents by market cap and weekly revenue, scored through Coral
Bot	glyphbots	A GlyphBot drawn from its Unicode, and the character sheet behind it
Womp	voxels	In-world photos, newest first, decoded straight to the panel
Gas	gwei	Base fee, three speed tiers, 24h sparkline, threshold alarm

• docs/API.md the five APIs, verified shapes, rate limits
• sim/README.md the simulator, and how it takes screenshots
• docs/PLAN.md what is built, and the flash gate nobody has run
• docs/ROADMAP.md build order
• CLAUDE.md rules

Every view is written and none of it has run on hardware. The screenshots came out of the simulator, which is why the simulator exists.

Hardware

Cardputer ADV (K132-ADV), three units. ESP32-S3FN8 (Stamp-S3A), 8MB flash. 240x135 ST7789V2. 56 keys via TCA8418. BMI270 IMU. ES8311 codec, 1W speaker, 3.5mm jack. MEMS mic. IR emitter. microSD. Grove HY2.0-4P + EXT 2.54-14P. 1750mAh. Magnetic back, LEGO holes.

Not the original v1.1: different keyboard controller (TCA8418 vs 74HC138), different audio (ES8311 vs NS4168+SPM1423), plus the IMU and the 3.5mm jack. GPS and LoRa are Grove/EXT modules, not onboard.

Build

pio run -t upload             # flash, then pio device monitor
pio run -e sim -t exec        # the simulator, which is how a view gets looked at
tools/fmt.sh                  # house style, --check enforces it
tools/apicheck/check.py       # ask the five sources whether they still fit

Everything but the first line runs without a device.

WiFi is typed on the device under Setup and kept in NVS, so a unit works for whoever holds it. For a dev unit that joins on first boot, cp include/secrets.h.example include/secrets.h; anything typed on the device wins over it.

M5Cardputer 1.1.1 is the first release that drives the ADV's TCA8418 keyboard. Older versions read no keys.

Layout

Path	Holds
src/main.cpp	boot report, the loop
src/net.*	WiFi, HTTPS with the bundled roots, JSON and streaming fetches
src/ui.*	the 240x135 layout, colors, status bar
src/view.*	view registry, menu, input, the exit convention
src/store.*	NVS settings
src/views/*.cpp	one file per view, each registering itself
src/coral.*	a Coral score and the two screens it is shown through
src/jpeg.*	a photo decoded off the socket, split per target like net
src/glyphs.h	generated: the 105 characters a GlyphBot is drawn from
src/ca_roots.h	the root CAs every host chains to
sim/	the simulator, and the captured fixtures its network answers from
tools/apicheck/	the contract check over all five sources
tools/fixtures/	compiles the captures into a header the simulator links
tools/glyphs/	builds the atlas from the collection's own alphabet

The four spine headers are frozen. A view adds itself with VIEW_REGISTER and never edits them.

Stock firmware

The device ships with M5Stack's UserDemo (CardputerADV branch, MIT), a useful HAL reference, on the upstream remote. Flashing ours replaces it and M5Burner puts it back, so with three units keeping one stock costs nothing. In that firmware home is the G0 button, not a key.