An ESP32-based automatic coffee brewing control system that interfaces with Bluetooth scales and Breville Dual Boiler espresso machines.
- Connects to BOOKOO Bluetooth scales
- Reads real-time weight and flow rate data
- Automated shot control based on target weight with dynamic learning
- WebSocket-based real-time weight updates
- Asynchronous web server for control and monitoring
- RESTful API endpoints for complete control
- Integration with Bru PWA for coffee brewing/bean tracking
- Weight triggered Preinfusion mode that uses low pressure until the first drops of coffee are detected (as an alternative to preinfusing for a pre-defined duration)
- OTA Updates using ESPAsyncHTTPUpdateServer
- Adaptive flow compensation that learns from previous shots
- Shot history storage for reference and flow compensation calculation
- Automatic sleep/wake to save energy and prolong scale battery life
- ESP32 development board
- Breville Dual Boiler espresso machine
- BOOKOO Bluetooth coffee scale
- Basic wiring for brew switch control
The custom PCB includes:
- 2x JST S11B-PH-K-S connectors
- One accepts stock female connector from machine
- One connects PCB to mainboard
- ESP32-S3-MINI module
- Mini360 buck converter (12V to 5V)
- 4-channel optocoupler for button control
- Only one channel needed for brew control
- Any brew button can stop an active brew
- e.g. 2-cup start → manual stop is valid
The PCB design allows for non-destructive installation by intercepting the stock button panel connector. Power is drawn from the machine's 12V line, converted to 5V for the ESP32.
The brew control is simplified since the Breville Dual Boiler allows any brew button to stop an active shot - you don't need to use the same button that started the brew to stop it.
- NimBLE-Arduino - Lightweight Bluetooth LE library
- ESPAsyncWebServer - Async HTTP and WebSocket server
- ESPAsyncHTTPUpdateServer - OTA Updates
- Install PlatformIO IDE extension in VS Code
- Clone this repository
- Build and upload to your ESP32 using PlatformIO
The device will automatically:
- Scan for BOOKOO scales
- Connect when found
- Begin receiving weight measurements
- Start the web server for control and monitoring
- Enable WebSocket connection for real-time data
The ESP32 hosts a web interface accessible via its IP address, offering:
- Real-time weight display via WebSocket
- Scale control (tare, timer functions)
- RESTful API endpoints for automation
/prefs- GET/POST brew preferences (enabled state, presets, preinfusion mode)/start- POST to start a brew with target weight/stop- POST to stop current brew/clear-data- POST to clear stored shot data/clear-shot- POST to clear a specific shot record/recalc-comp-factor- POST to force recalculation of the flow compensation factor/wake- POST to wake ESP from sleep mode/data- GET shot history and flow compensation factor
/ws- WebSocket endpoint for real-time brew metrics (weight, flow rate, target weight, time, brew state)
The system implements an automatic activity management system that:
- Puts the device to sleep after 10 minutes of inactivity
- Disconnects from the scale to save battery life
- Wakes on any button press or via wake API endpoint
The system includes a learning algorithm that tracks shot history and automatically adjusts timing to ensure the final brew weight matches the target weight. This compensation factor:
- Is calculated based on weighted average of past shots
- Gives priority to more recent shots
- Adapts gradually with each brew
- Can be manually recalculated
- Is stored in persistent memory
This is currently a work in progress. Future updates will include:
- Further integration with bru PWA