DragonVent

Open firmware for the BIGTREETECH Panda Vent, built on the shared dragon-core networking and printer-integration components.

What is this?

The Panda Vent is a smart vent riser for enclosed 3D printers. DragonVent replaces its stock firmware and currently integrates with Klipper printers through Moonraker while preserving the proven OpenVent motor, hall-sensor, button, and vent-policy implementation.

Screenshots

The device serves a responsive web UI over your LAN (also embeddable in the Fluidd / Mainsail panel): live vent controls with the automatic printer-following policy, and a Lighting page for the WS2812 status strips — effects, colors, and per-strip direction.

Features

Working today:

• Automatic vent control — six-state printer model (idle / preparing / printing / paused / complete / error), material-aware policy (PLA opens for cooling, ABS/ASA seals for heat retention), bed-temp hysteresis for residual heat
• Stock-parity hall sensing — per-boot ADC line-fitting calibration with calibrated-millivolt thresholds, matching stock's reproduction contract
• Dragon-family dashboard — responsive DragonVent-flavoured control UI for live vent/source state, manual open/close, and automatic threshold policy
• Unified browser management — the shared Dragon SPA is used on the LAN and on the captive setup AP, with integrated Wi-Fi, printer-source, OTA, logs, and reset controls
• Moonraker integration — WebSocket ingest with webhooks / print_stats / virtual_sdcard / heater_bed / extruder / optional chamber + save_variables (for material), re-subscribes on Klippy restart
• Bambu LAN integration (experimental) — optional read-only MQTT source using the printer's LAN access code; DragonVent never sends printer-control commands. The shared client and portal path build cleanly, but still need validation against a real Bambu printer
• Single-source binding — select Klipper, Bambu LAN, or standalone mode; only the selected printer client starts
• Configurable thresholds — bed OPEN/CLOSE °C editable in the portal, persisted to NVS
• Physical button control — auto/manual mode toggle, manual vent override, manual target persists across reboots
• Schema-driven setup — product-specific source and vent-policy fields are rendered by the common SPA instead of a second firmware page
• OTA firmware updates — flash new firmware from the web UI
• RGB status lighting — WS2812 strips with effects (solid, cycle, rainbow, breathe, strobe, wave, marquee, Cylon), printer-status colors, a temperature gradient, an error flash, and per-strip reverse for 2-strip kits (run both strips the same direction or opposite, so effects can "circle" the printer)

Documentation

• Hardware Analysis — reverse-engineered GPIO pinout and hardware details
• Roadmap — development phases and architecture

Hardware

• Kit contents: 1 mainboard + several motorized vent modules + LED boards. Each vent module has one motor, one hall sensor, and identical 3-pin JST connectors on both ends — so multiple modules chain together
• Board: Bigtreetech Panda Vent (ESP32 Xtensa dual-core LX6)
• Motors: up to 4 independent DC motors across two mainboard chains, each driven forward/reverse via LEDC PWM at 30 kHz with hall-sensor position feedback
• LEDs: WS2812 addressable strips via SPI + DMA — GPIO 14 and GPIO 4, one per chain
• User button: switch on GPIO 12, illumination LED on GPIO 27 (off = auto, blink = manual)
• BOOT button: GPIO 0 (long-press = factory reset)
• Hardware auto-detect: single ADC on GPIO 35 picks between "all chains populated" (4 motors), "one chain" (2 motors), and "nothing" — hot-plug supported

Full pin map + provenance: docs/HARDWARE_ANALYSIS.md.

Install — over stock, from a browser (v0.5.0+)

As of v0.5.0 DragonVent runs on the stock Panda Vent partition table, so you install and update it entirely from the web UI — no serial cable, no helper scripts. The stock bootloader is preserved; only the app slot is written.

1. Grab dragonvent-<tag>-ota.bin from the latest release.
2. Open the stock Panda Vent's web UI (http://PandaVent.local/ or its IP) and upload the ota.bin on its firmware-update page. It writes DragonVent to the inactive slot and reboots into it.
3. First boot is the DragonVent_XXXX setup AP (WPA2, password 987654321); join it to set WiFi + printer. Afterwards it's on mDNS at DragonVent.local.

Updating an existing DragonVent is the same file, from Device setup → Maintenance in the DragonVent web UI.

⚠ Back up stock first — BTT publishes no Panda Vent image, so dump the flash over USB before your first install; it's your only way back:

python -m esptool --chip esp32 -p PORT -b 460800 read_flash 0x0 0x400000 stock-panda-vent-backup.bin

Upgrading from 0.4.x: those builds used a different partition table, so you can't OTA straight across. Write your stock backup back over USB, then install over stock from the web UI (same one-time roll-back as the DragonBreath 1.0 migration). 0.5.0+ update in place.

python -m esptool --chip esp32 -p PORT -b 460800 write_flash 0x0 stock-panda-vent-backup.bin

Status

DragonVent is the continuation of OpenVent. The first refactor keeps the v0.3.3 hardware behavior and NVS layout while moving WiFi, Moonraker, and event logging onto pinned dragon-core components.

OpenVent v0.3.3 restored stock ADC calibration parity. Reverse-engineered against the Ghidra decompile of stock v1.0.0 — see docs/adc-calibration-spec.md for the reproduction contract. This unblocks per-board hall-sensor accuracy without requiring per-board threshold tuning.

Prior milestone: v0.2.6 was the first stable proof-of-concept release. 2026-07-10 field test on tester OldGuyMeltsPlastic's retail 2-vent kit: 10× consecutive open/close cycles, no ESP crash, motor stops cleanly on each arrival.

• ✅ Motors drive both directions and reliably stop at endpoints, using stock-parity mV thresholds and per-boot ADC line-fitting calibration
• ✅ Six-state printer model + material-aware auto policy, re-subscribes on Klippy restart
• ✅ Firmware flashes on real Panda Vent hardware; dragonvent script for backup / restore / install works end-to-end
• ✅ WiFi station + AP fallback, mDNS DragonVent.local, captive portal
• ✅ Unified SPA management: live vent controls plus schema-driven Wi-Fi, printer-source, fallback-AP, event-log, OTA, and factory-reset setup
• ✅ WS2812 RGB status lighting — effects, printer-status colors, and per-strip reverse (shipped in the 0.5.x series)

License

MIT © Justin Hayes