ESP32-S3 Coffee Roaster Controller - BLE & App

What is it?

A smart, high-precision controller board designed specifically for DIY and home fluid-bed (hot air) coffee bean roasters.

Why did you make it?

Having to tether a laptop running Artisan to your roaster every time can be cumbersome and messy. I wanted a truly standalone, wire-free roasting experience. This custom controller board comes with a dedicated mobile companion app, allowing you to monitor roast curves, log data, and control the entire roast directly from your smartphone or tablet.

Check out the previous build log and discussion on Reddit:

https://www.reddit.com/r/roasting/comments/1w73fvc/i_built_a_custom_esp32s3_controller_for_a_hotair/

What makes it special?

1. 3-Channel Temperature Sensing:BT (Bean Temp) & ET (Exhaust Temp): High-accuracy 3-wire PT100 RTD probes.
2. IT (Inlet Temp): K-Type thermocouple (fully compatible with common 5-wire heat gun heating elements).
3. Ambient Environment Monitoring: Onboard ambient temperature and relative humidity sensing, making it effortless to adjust your roast profile based on daily weather conditions.
4. Heater Control via SSR: Precise 0–100% power regulation via Solid State Relay. Supports SSRs with trigger voltages below 3.3V.
5. Brushless Motor / Fan PWM Control: High-frequency 10 kHz PWM output for smooth, quiet, and precise airflow adjustment (0–100%).
6. Wide DC Input Voltage (9–36V DC): Highly versatile power compatibility. A universal wide-voltage AC/DC power adapter is included for free!

Companion Mobile App Features:

1. Cross-Platform: Supports Android, iOS, and iPadOS.
2. Free & Offline-First: No accounts, no cloud lock-in, and 100% privacy-friendly. Includes WebDAV support for seamless cloud backup and sync.
3. Clean UI/UX: Intuitive interface designed for one-handed operation while roasting.
4. Automated Profiles & PID Control: Supports automated background profiles. PID parameters can be directly adapted from your existing Artisan settings.
5. Live Curve Display & Editing: Real-time plots for Bean Temp (BT), Rate of Rise (RoR), and Inlet Temp (IT). Built-in support for Drying / Browning (Maillard) / Development.
6. Green Bean Inventory: Keep track of your green coffee origin, processing method, and stock.
7. Comprehensive Roast Logs: Automatically records roast history, roast loss (weight-loss %), green bean batch details, notes, and photo attachments.

What's Included:

1. 1x ESP32-S3 Coffee Roaster Controller Board (pre-assembled in 3D-printed enclosure, case color may vary / sent randomly)
2. Free iOS & Android Companion App (Free download with real-time monitoring, curve control, and regular updates)
3. 1x AC-DC Power Supply Module (Input: 100–240V AC, Output: 24V DC 250mA)
4. 1x Power Cable (~20cm, 1.0mm² / ~17AWG, pre-stripped ends, Blue/Black)
5. 1x Solid State Relay (SSR) Control Cable (XH2.54 2-Pin to insulated spade/fork Y-terminals, Red/Black)
6. 1x PWM Signal Cable for Brushless Motor (XH2.54 3-Pin to pre-stripped/tinned ends, Yellow(VSP)/Red/Black)
7. 1x XH2.54 3-Pin PCB Male Connector / Header (spare part)
8. 4x M3 Self-Tapping Screws (for mounting/assembly)

Need Extra Components? (Optional Add-ons)

Looking to build a complete setup? Feel free to contact me before placing your order if you need extra matching hardware, such as:

1. 40A DA Solid State Relays (SSR)
2. 500W 3-Phase Brushless DC (BLDC) Motor Drivers
3. 120W Brushless DC (BLDC) Motors
4. Custom wiring harnesses, cables, or expansion modules

Roadmap & Planned Features (TODO):

1. Automatic First Crack (FC) Detection: Upcoming firmware/hardware support for coffee roasting first crack recognition (acoustic/audio sensing).

⚠️ Important Safety Notes & Logic:

1. Emergency Switch: An independent physical switch for the heater is required as an emergency cutoff measure.
2. Low Temp Cutoff: When connected via the APP to the ESP32, both heat and fan speed will automatically drop to 0.
3. Bluetooth Disconnect: If Bluetooth disconnects unexpectedly, the APP will display a disconnection alert, and the device will maintain current heat and fan levels without disruption.