Brewberry π

Given a DS18B20 temperature sensor, a solid state relays and a wifi connector, automate the mash process.

At least, that's the plan.

This repo contains the code of my brewberry-π home brew software, built with Elixir and Nerves.

Brewberry π can:

• control temperature within a 0.1 °C margin
• read, set and control the mash process with your phone (web ui)
• brewing software can be upgraded over the network
• it's firmware, so you can pull out the plug at any time

Why Elixir/Nerves? Well...

• Elixir is build on Erlang technology, making it fault tolerant by design.
• Nerves provides a basis for real firmware. You can just pull out the power plug without bad things happening (you do not want to try that with Rasbian).
• The system is up and running in less than 6 seconds(!) (not including wifi authentication). This is a lot faster than the 60 seconds it takes for Rasbian to boot.
• The Erlang/Elixir actor model is a natural fit for message driven applications.

An older version of the Brewberry-π written in Python is available at https://github.com/amolenaar/brewberry-pi-python.

Get started

• Go to the web application with cd apps/web
• Run mix deps.get
• MIX_ENV=dev iex -S mix will lauch the app and open a console, so you can tinker around
• Open a browser on http://localhost:3030, the (web) app will be running there in "fake" mode

Firmware

To build an image for the Raspberry Pi (model B):

• Ensure Nerves stuff is installed on your machine, check out the Nerves getting started guide
• Go to the firmware application with cd apps/fw_rpi
• Install dependencies with MIX_ENV=prod mix deps.get
• Copy apps/fw_rpi/config/wifi-example.exs.example to apps/fw_rpi/config/wifi.exs and fix the ssid and psk properties
• Create firmware with MIX_ENV=prod mix firmware
• Burn to an SD card with MIX_ENV=prod mix firmware.burn
• And do remote updates once your first image is up and running: MIX_ENV=prod mix firmware.push 10.192.168.122 --firmware ../../_build/rpi/prod/nerves/images/fw_rpi.fw

PCB

To control a brewing kettle some additional hardware is required:

• http://learn.adafruit.com/adafruits-raspberry-pi-lesson-11-ds18b20-temperature-sensing
• http://en.wikipedia.org/wiki/Solid-state\_relay

A schema is made with Fritzing and is available in the file Brouwerij.fzz.

Bill of Materials

Label	Part Type	Properties
-	-	PCB prototype board
J1	Screw terminal	3 pins, connector to DS18B20
J2	Power plug	connector to SSR
Pi1	Adafruit Pi Cobbler	manufacturer Adafruit Industries
Q1	NPN-Transistor	type NPN (EBC); package TO92 [THT]
R1	4.7kΩ Resistor	pullup resistor
R2	1kΩ Resistor

Learn more

• Elixir: http://elixir-lang.com
• Nerves docs: https://hexdocs.pm/nerves/getting-started.html
• Nerves website: http://www.nerves-project.org/

TODO

• Use bootloader from https://github.com/mobileoverlord/bootloader