Lightning powered beer tap

This project consists of multiple parts. To make things easier the application.sh provides a frontend to control everything. The different parts of the project are documented below.

Parts list

To build your own lightning powered beer tap you'll need the follwing parts. We got most of our parts from distibutors located in switzerland, but you can get them anywhere you want.

Partname	Partnumber	Price / CHF	Distributor
Raspberry Pi 3 B+	10760	39	pi-shop.ch
32GB MicroSD Card	6613018	29.9	digitec.ch
Original Rpi 7" Touchscreen	10266	79.9	pi-shop.ch
PiggiPi 7’’ Display Mount	10399	48.9	pi-shop.ch
Raspberry Pi Relay Board	10398	24.9	pi-shop.ch
24V AC Source (24W/50Hz)	169-84-752	22.7	distrelec.ch
Beer tap with solenoid valve	08.00125	247.3	schankanlagenhandel.eu
Bent faucet for beer tap	08.00128	22.51	schankanlagenhandel.eu

Installation

This is straightforward. If you bought an empty micro-sd card, just download the latest Raspbian image.

• Fire up dd to load the image to your card.
• Use sudo raspi-config to extend your partitions, start openssh and enable the gpios.
• Follow the guide on how to secure you raspberry pi
• Once you've deployed your ssh key and secured your acces, clone this repo.
• Install the necessary software to your pi by executing the following commands:

sudo apt-get update
sudo apt-get install -y  openjdk-8-jre openjdk-8-jdk unclutter vim

• Add your user to the group gpio
• You're all set and ready to go

Aplication.sh start script

This script is used to start, stop or rebuild the application. Simple as that. The websocket bridge will be automatically builded if you run start without a previous build.

$ ./application.sh start # starts the dashboard and websocket bridge
$ ./application.sh stop  # stops everything
$ ./application.sh build # rebuilds the java websocket bridge

WebSocket Bridge

build application

./gradlew build

how to run

get the built application from ./build/libs

java -jar websocket-bridge-0.0.1-SNAPSHOT.jar --url=wss://ln-self-order-pos-dev.ose3.puzzle.ch/websocket/invoice?access_token= --topic=/topic/invoice --command=./dummy_command.sh

Options:

• url: the websocket to connect to
• topic: the topic to subscribe to
• command: the shell command that is executed when a message was received on the websocket

Two Options will be routed to the shell command that is executed

• --memo
• --products

for example:

./dummy_command.sh --memo="puzzleUp #9c4a Grey Card (CHF 5.00)" --products=PRODUCT_1

GPIO handler

To execute this python module the user has to be part of the group gpio.

Dependencies

• RPi-GPIO (preinstalled on all raspberry pi distros)
• argparse

how to run

$ python gpio_handler.py --product=[large,small] [--test, --memo="asdf"]
$ python gpio_handler.py --help