coffee-pi

A Raspberry Pi modification to the Rancilio Silvia Espresso Machine implementing PID temperature control.

Currently Implemented Features:

• Brew temperature control
• RESTful API
• Web interface for displaying temperature and other statistics
• Programmable machine warm-up/wake-up

Planned Features:

• Steam temperature control
• Timed shots with pre-infusion
• Digital pressure gauge

Dashboard

Hardware

• Raspberry Pi
• Power Adapter (old iPad charger)
• Micro SD Card
• Solid State Relay - For switching on and off the heating element
• Thermocouple Amplifier (e.g. MAX31855) - For interfacing between the Raspberry Pi and Thermocouple temperature probe
• Type K Thermocouple - For accurate temperature measurement
• Cables and wires

Hardware Installation

Installation Instructions / Pictures

GPIO Connection Table

GPIO Pin	Destination
3.3 V	VCC MAX 31855K
Ground	Solid State Relais -
Ground	GND MAX 31855K
Ground	Main Power Switch -
Ground	Green Power LED -
GPIO 4	Solid State Relais +
GPIO 8	CS MAX 31855K
GPIO 9	SO MAX 31855K
GPIO 11	SCK MAX 31855K
GPIO 12	Main Power Switch +
GPIO 16	Green Power LED +

coffee-pi Software Installation Instructions

First, install Raspbian and configure Wi-Fi and timezone.

Then, execute the following code in the pi bash shell:

sudo apt-get update
sudo apt-get upgrade -y
sudo apt-get install -y rpi-update git build-essential python-dev python-smbus python-pip
sudo rpi-update
sudo bash -c 'echo "dtparam=spi=on" >> /boot/config.txt'
sudo reboot

Then install berryconda3 (change the default directory to /home/pi/miniconda3):

wget https://github.com/jjhelmus/berryconda/releases/download/v2.0.0/Berryconda3-2.0.0-Linux-armv7l.sh
sudo /bin/bash Berryconda3-2.0.0-Linux-armv7l.sh

After a reboot, clone the coffee-pi repo:

git clone https://github.com/alexarnimueller/coffee-pi.git /home/pi/coffee-pi
cd /home/pi/coffee-pi

Then run the following command to create a new conda environment and install the necessary packages:

conda create env -f environment.yml
pip install poetry
poetry install

Finally, edit your crontab to run the coffee-pi script at reboot by typing crontab -e and adding the following line at the bottom of the file:

@reboot /home/pi/miniconda3/envs/coffee-pi/bin/python /home/pi/coffee-pi/app/app.py

API Documentation

GET /allstats

GET /brewtemp

Returns the current brew temperature in °C

POST /brewtemp

Sets the desired brew temperature in °C

GET /scheduler/{on,off}

Turns the scheduler on or off

GET /restart

Issues a reboot command to the Raspberry Pi.

GET /turnon

GET /turnoff

GET /healthcheck

A simple healthcheck to see if the webserver thread is repsonding.
Returns string 'OK'.