Hardware
Two airflow options
Build it with the stock popper fan and DC speed control, or use the printed ASA fan with a brushless 12 V motor.
Weekend project: DIY Coffee Roaster
An open-source coffee roaster built from a modified popcorn popper, a cheap touchscreen, and a few other things.
See the roaster in action
A quick look at the hardware and the roasting process.
Everything you need
This project includes hardware BOMs, software, 3D printed parts, and build documentation.
Build
Documented assembly flow
The build guide covers printed parts, breakout-board assembly, popper modification, wiring order, and first power-up checks.
Firmware
Controller and web tools
The JC4827W543C firmware includes the touchscreen UI, profile editor, debug console, PID workflow, OTA updates, and a REST API.
Artisan
External roast logging
Connect the roaster to Artisan over WebSocket for live roast curves, logging, and post-roast analysis.
Read the docs
Use these guides for the hardware build, parts list, firmware workflows, and Artisan setup.
Guide
Build instructions
Step-by-step assembly instructions with printed-part references, breakout-board guidance, wiring details, and build photos.
Guide
Bill of materials
Parts list with Amazon and AliExpress sources, two motor-build variants, and notes for the JC controller wiring and popper conversion.
Guide
Firmware workflows
Bootstrap, build, upload, OTA, tests, and runtime interfaces for the JC4827W543C firmware target.
Guide
Artisan setup
WebSocket logging setup, settings import, screenshots, and first connection steps for Artisan.
Software
The firmware runs on the JC4827W543C ESP32-S3 display board and is documented separately from the hardware build. The runtime surface includes the touchscreen UI, browser tools, OTA updates, and Artisan-compatible data streaming.
Roast profiles
Define time / temperature / fan setpoints. The firmware interpolates between them during the roast. Profiles are stored on-device and editable from the browser.
PID temperature control
Closed-loop PID keeps the roasting chamber on target. Dual thermocouples monitor chamber and exhaust temperatures.
Integrated touchscreen
The JC4827W543C panel shows real-time temperatures, profile progress, PID workflow screens, and system status directly on the device.
Web interface
Profile editor, debug console, and live status at roaster.local. OTA firmware updates without opening the case.
Artisan integration
Streams roast data over WebSocket to Artisan for real-time curves, logging, and analysis. Config files included.
REST API
Full API for profiles, PID tuning, roast control, and system status. OpenAPI spec in the repo.
Safety
This project controls line voltage and high temperatures. The firmware has safety systems, but understand the risks before building.
Over-temperature cutoff — heater shuts off if chamber temp exceeds safe limits.
Sensor validation — thermocouple faults and implausible readings trigger error state.
Fail-safe defaults — heater OFF, fan ON. Unknown states enter ERROR, not IDLE.
Cooling lockout — can't skip cooling until chamber is below a safe threshold.
Get started
Start with the build guide and BOM, then follow the firmware and Artisan docs as you bring the roaster online.