BrewPi on Bluetooth

Over on Homebrew Talk, @day_trippr shared a way to connect the Arduino to your Raspberry Pi over Bluetooth. That was December 14, 2014 and a lot pf people have been successful with that. I personally found a couple of the steps a little challenging. To be fair, that’s a personal shortcoming and not one of the original article. Still I searched for a way to make it a little easier and I think I’ve found it. I’ll share here what I’ve come up with in the hopes that someone else will find it useful.

This tutorial is for Windows users. I expect Mac and Linux users will have to use the “old fashioned” way.

On Amazon I found a package with an HC-05 Bluetooth Module, a case for that module, Dupont jumpers, and a CP2102 USB to TTL Converter for $12.99 on Prime. That seems like a pretty good deal and provides some pretty good value for a person new to it. When you get a drawer full of “crap”, the Dupont wires certainly have less value, but I kinda like the case. So, I’m writing this with that USB to TTL Converter being used:

You can find it on Amazon here. Buy that and come back.

Hardware Setup

Without further adieu, let’s get started. Don’t plug the adapter in your computer yet. You’ll need to download some software to get going. You’ll probably need the CP2102 drivers, and to follow this you will definitely need the DSD TECH Bluetooth Tools Software. Download and install both of these (actually the “Bluetooth Tools” doesn’t install, just unzip to a handy directory):

Don’t plug the converter into the USB on your computer yet. Connect the TTL converter and the BT module like so:

I actually used the 3.3v the first time, the module will run on 3.3-6v for VIN I believe, but the data channel needs to be 3.3 volts. No worries, the USB to TTL converter handles that for you. Here’s the connections in text form:

Converter PinHC-05 Pin

Basically, remember to connect transmit to receive and vice versa. When you are ready and the jumpers are connected properly, connect the device and set programming mode (called “AT mode”) by doing the following:

Input low level to PIN34, supply power to the module, input high level to PIN34, then the module will enter to AT mode.

Just kidding, I have no idea what that means either. I promised this would be for mortals. 🙂

  1. Hold the button down on the Bluetooth Module (note about some of the modules sold elsewhere which are insulated with shrink-tube: You may have to cut the tube away from the button in order for it to function correctly)
  2. Plug in the USB to TTL Converter
  3. The light will come on for about a second, and then shut off
  4. Let go of the button on the Bluetooth Module

If you have done this correctly, the module should be flashing on and off slowly. Done incorrectly, the device will be flashing rapidly. If you don’t get it the first time, unplug the converter and try again.

Now run the “DSD TECH Bluetooth Tools Software” you unzipped. You will be executing “SHTester.exe”.

  1. Select the last tab which is “HC-05”.
  2. Drop down the UART box and select the port. On most systems there will be only one. If you have some other COM port device installed there may be more than one listed. If this is the case you will need to open Windows’ “Device Manager”, look under “Ports (COM & LPT)”, and see what COM port is associated with the “Silicon Labs CP210x” device.
  3. Set Baud Rate to 38400, then click “Open”.
  4. Click the “Test” button, and in the status windows you will see the “AT” command being sent and “OK” received. This will not work unless you are in AT mode (slow flashing). If you don’t get anything back it’s likely a Baud Rate mismatch. Click on “Close”, select a different Baud Rate, “Open” and try testing again till you get an “OK” back.
  5. Now set “Bluetooth Name” to whatever you’d like it to be, Baud Rate to 57600, PIN (really no reason to change the PIN but if you do, remember it), and set Role to “Slave”. Click “Set” after each change.
  6. Now “Close” the UART up top again with the red “X” and you can close the app.

If you’d like, you can test the device over Bluetooth from your computer:

  • Unplug the USB dongle and unplug the two TX and RX wires.
  • Plug it back in and now the Bluetooth Module will be flashing rapidly indicating it’s ready to be paired.
  • Open the Windows Bluetooth settings and click “Add a device.”
  • Select the name you gave the module above and enter the PIN you used.
  • Click “Connect” and if successful, the device will flash briefly every two seconds or so.

Congratulations! You can unplug the device now, it’s ready to be connected to your Arduino.

This is where you can go a couple different ways. In order to connect to your Arduino you do need to either use a voltage splitter to step the voltage down to 3.3v, or if you are using @CadiBrewer’s shield, this is done for you. This has to be done because the logic on the HC-05 module can only handle 3.3 volts, and the TX channel on your Arduino is at 5 volts.

If you are using the shield version 1.1, connect as follows:

Shield PinHC-05 Pin

If you are using the shield version 1.2, reportedly the RX/TX line up directly so connect as follows:

Shield PinHC-05 Pin

If you are going all rogue and want to do it without a shield, at least you were able to skip the whole Arduino sketch setup thing initially. You will need the following:

  • 1 x 1K ohm resistor (1/8W axial)
  • 1 x 2K ohm resistor (1/8W axial)
  • Assorted Dupont jumpers

Wire them according to this diagram so that the voltage into the RXD pin on the module is cut to 3.3v:

Software Setup

Setting this all up changed since the article @day_trippr posted. I am NOT sure when this changed. @day_trippr is running Wheezy and Jessie and his original article uses the “old” way of setting up a Bluetooth device. I’m using Stretch with bluetoothd 5.43 and the method by which you set up /dev/rfcomm* devices with the rfcomm.conf file in /etc/bluetooth in Wheezy and Jessie is no longer supported. I’m sure someone somewhere could tell me WHY this is better. I’m sure we’d hear some crap about “cloud-enabled” like they tell me with all my favorite Ubuntu items that no longer work.

Anyway, here’s how you can get the devices enabled with Stretch. To start with, make sure your HC-05/6 is powered up in its production configuration (i.e. baud rate and slave mode as detailed above). At this point it’s probably flashing 2-3 times per second. Then, prove to yourself that there’s no rfcomm* devices:

pi@brewpi:~ $ ls -al /dev/rfc*
ls: cannot access '/dev/rfc*': No such file or directory

Next, execute the new CLI for bluez, “bluetoothctl”:

pi@brewpi:~ $ sudo bluetoothctl
[NEW] Controller XX:XX:XX:XX:XX:XX brewpi [default]

The controller listed is your local Raspberry Pi’s controller. We need to turn on and configure the “agent” which is the process that allows you to enter the pairing codes with Bluetooth devices when required:

[bluetooth] # agent on
Agent registered
[bluetooth]# default-agent
Default agent request successful

The next thing to do is allow the system to scan for local devices. If you have a “busy” area bluetooth-wise, you may get a lot of spam. Just let it run about 10 seconds and if you are living a clean life you will see your target Bluetooth device and it’s MAC address. After that you can turn off the scan.

[bluetooth]# scan on
Discovery started
[CHG] Controller XX:XX:XX:XX:XX:XX Discovering: yes
[NEW] Device XX:XX:XX:XX:XX:XX [TV] Living room
[NEW] Device XX:XX:XX:XX:XX:XX Chamber 1
[bluetooth]# scan off
Discovery stopped
[CHG] Controller XX:XX:XX:XX:XX:XX Discovering: no

You may have to scroll up to find it, but if you gave your HC-05 a friendly name when you set it up (“Chamber 1” in my case), you should see the MAC followed by that name. Next, you will pair with your device with the pair command followed by the MAC address. It will prompt you to enter the code which is generally 1234 or 0000 unless you changed it:

[bluetooth]# pair XX:XX:XX:XX:XX:XX
Attempting to pair with XX:XX:XX:XX:XX:XX
[CHG] Device XX:XX:XX:XX:XX:XX Connected: yes
Request PIN code
[agent] Enter PIN code: 1234
[CHG] Device XX:XX:XX:XX:XX:XX UUIDs: 00001101-0000-1000-8000-00805f9b34fb
[CHG] Device XX:XX:XX:XX:XX:XX ServicesResolved: yes
[CHG] Device XX:XX:XX:XX:XX:XX Paired: yes
Pairing successful
[CHG] Device XX:XX:XX:XX:XX:XX ServicesResolved: no
[CHG] Device XX:XX:XX:XX:XX:XX Connected: no

Next you will “trust” the HC-05:

[bluetooth]# trust XX:XX:XX:XX:XX:XX
[CHG] Device XX:XX:XX:XX:XX:XX Trusted: yes
Changing XX:XX:XX:XX:XX:XX trust succeeded

At this point your BT dongle is probably flashing once every two seconds. It’s paired and trusted as you can see by issuing the ‘info’ command:

[bluetooth]# info XX:XX:XX:XX:XX:XX
Name: Chamber 1
Alias: Chamber 1
Class: 0x001f00
Paired: yes
Trusted: yes
Blocked: no
Connected: no
LegacyPairing: yes
UUID: Serial Port (00001101-0000-1000-8000-00805f9b34fb)

I noticed that if you power-cycle the Bluetooth device at this point, it will go back to flashing 2-3 times/second but that doesn’t seem to affect things. You can exit or quit back to the shell prompt:

[bluetooth]# exit
Agent unregistered
[DEL] Controller XX:XX:XX:XX:XX:XX brewpi [default]
pi@brewpi:~ $

So, it’s paired and trusted but still not visible in the device list as you can see if you list it out:

pi@brewpi:~ $ ls -al /dev/rfc*
ls: cannot access '/dev/rfc*': No such file or directory

To add it to the device list, we need to bind it to a device with the following command:

pi@brewpi:~ $ sudo rfcomm bind 0 XX:XX:XX:XX:XX:XX 1 > /dev/null 2>&1 &
[1] 3345

It seems like the command runs till something touches the device (which is why we background it with the trailing ‘&’.) In that command the ‘0’ is the rfcomm device we want to assign (i.e. /dev/rfcomm0), the MAC address should be obvious, and the 1 is the channel. Unless you know why you want to change the channel, use ‘1’. Now prove there is a device in the list (and see the background process exit):

pi@brewpi:~ $ ls -al /dev/rfc*
crw-rw---- 1 root dialout 216, 0 Mar 16 13:31 /dev/rfcomm0
[1]+ Done sudo rfcomm bind 0 XX:XX:XX:XX:XX:XX 1 > /dev/null 2>&1
pi@brewpi:~ $

Power-cycling the BT device at this point proves the device will reconnect after a power failure after about 10 seconds. What does not happen however is the connection will not re-establish to the device after a Raspberry Pi reboot or power failure. We need a way to issue the rfcomm command after every reboot (and after the bluetoothd starts.) Create a file named ‘rfcomm0.service’ in the ‘/etc/systemd/system/’ directory:

sudo nano /etc/systemd/system/rfcomm0.service

Add the following information:


ExecStart=/usr/bin/rfcomm bind 0 XX:XX:XX:XX:XX:XX 1 > /dev/null 2>&1 &


This will allow systemd to execute the rfcomm command binding that MAC to rfcomm0 after the bluetooth.service starts. To enable this unit file, issue the commands:

pi@brewpi:~ $ sudo chown root:root /etc/systemd/system/rfcomm0.service
pi@brewpi:~ $ sudo chmod 664 /etc/systemd/system/rfcomm0.service
pi@brewpi:~ $ sudo systemctl daemon-reload
pi@brewpi:~ $ sudo systemctl enable rfcomm0
Created symlink /etc/systemd/system/ → /etc/systemd/system/rfcomm0.service.
pi@brewpi:~ $

You can start it with the ‘sudo systemctl start rfcomm0’ command, but there’s no reason to since it’s already bound (assuming you ran the bind command above and have not rebooted – it will not hurt if you run it again). If you check the status of this daemon after system reboot it will not be running, because it ran once and exited – which is all we needed it to do:

pi@brewpi:~ $ sudo systemctl status rfcomm0
● rfcomm0.service
Loaded: loaded (/etc/systemd/system/rfcomm0.service; enabled; vendor preset:
Active: inactive (dead) since Sat 2019-03-16 13:43:59 CDT; 40s ago
Process: 290 ExecStart=/usr/bin/rfcomm bind 0 XX:XX:XX:XX:XX:XX 1 > /dev/null 2>&1 & (code=exited, status=0/SUCCESS)
Main PID: 290 (code=exited, status=0/SUCCESS)
Mar 16 13:43:59 brewpi systemd[1]: Started rfcomm0.service.

That’s how you set up your BT devices now in Stretch! You’ll notice that using the graphical interface is also not needed. Using this method, no additional packages are required as a matter of fact, all the packages are part of the stock Raspbian Stretch distribution.

If you have multiple Bluetooth devices, you’d change the above steps using 1, 2, 3, etc., instead of 0. You would also need a systemd unit file for each device named appropriately.


If you want to give it a test outside of BrewPi, you will need to install a program called “screens”:

sudo apt install screen

Next, run ‘screen’ and connect to that device with the proper baud rate:

sudo screen /dev/rfcomm0 57600 

If you are living a clean life, you are now connected to your Arduino. Issue the command ‘l’ (lower-case L) and the controller should print the LCD screen information; something like this:

L:["Mode   Off          ","Beer   60.7  --.- �F","Fridge 61.2  --.- �F","Idling for     03m08"

You need to type “ctrl-a” and then “k” to kill the screen session.

Configure BrewPi

In order to connect this to BrewPi, you will edit (or create) your config.cnf file to look something like the following:

scriptPath = /home/brewpi
wwwPath = /var/www/html
port = /dev/rfcomm0

This works in Legacy BrewPi as well as all versions of BrewPi Remix.

BrewPi on WiFi

One of the most common “wishes” for BrewPi users is to be able to connect the Raspberry Pi to the Arduino wirelessly. This makes even more sense and is more desirable when you leverage a multi-chamber setup. The Arduino Uno did not have WiFi originally, although the nice folks over there in Italy have a Rev 2 of a WiFi enabled Uno for the low low price of $44.90. I don’t know for sure, but since (I believe) this is a native implementation, I suspect any Uno sketches would need to be re-written for WiFi.

That’s a problem for BrewPi where we are getting close on storage space anyway.

Not to fear though! Back in 2015, @thekraken on HomebrewTalk started talking about how to make an ESP8266 work as a serial bridge. That was really just sort of a technical discussion, and it never quite rose to the level of something that seemed practical for most end users. About four months after that, @day_trippr took a swing at it and came up with a start to finish method of doing it for the courageous, but let me just tell you that dude is “wicked smaht” and what’s easy for him is not generally easy for a guy like me.

People kept pecking at it but rather than me give you the blow by blow, you can read it yourself on HomebrewTalk. BUT, I figure you want to know how to do it, or else, why are you here. Amirite?

So, here’s what you need:

  • A Raspberry Pi (duh!)
  • A combo ATmega328P+ESP8266 card direct from China. The ATmega328 is the guts of an Uno. The ESP8266 is a controller in its own right, but we are using it as a WiFi/Serial bridge. I used this one from Banggood in my project. I don’t have any reason to believe that there are not many others that would work. I paid $6.49 + shipping so I bought a couple just in case one arrived DOA.

To start with, go ahead and install BrewPi Remix if you don’t have it installed already. No need to connect the Arduino just yet. Take the defaults, smile and nod your head if the script tells you there’s no Arduino, and don’t worry about flashing the controller (yet.)

You might need to Google up some drivers for the CH340 chip if you will be using your PC for this (and expect my instructions to work), unless you’ve messed with one of the Uno clones before. The “official” drivers appear to be on this page in Chinese. You can either translate or click on the very obvious download button and throw caution to the wind.

Install those drivers, and find yourself a USB micro cable because this board ditched the HUGE type “B” plug. Before you plug it in, you need to set the DIP switches as follows to let the CH340 talk to the ESP8266:

Switch NumberPosition
8 (Do Not Use)Off

Go ahead and plug the board in to your PC to hear the pleasing “boing” letting you know that it connected. You’ll need the NodeMCU Firmware Programmer if you have not already downloaded it before. You can get it here. If you don’t know whether you are on a 32 or 64-bit system, just grab the ESP8266Flasher.exe file from the Win32/Release directory.

You will also need some firmware for the ESP8266 side. First, download “ESP-Link” version 3.0.14 from the releases page (read the notes and get the latest stable version.) Previous versions of this article had instructions to use 2.2.3 versions, but the 3.0.14 firmware seems quite stable. Unzip those files somewhere handy and continue.

Go ahead and execute the NodeMCU Firmware Programmer (“ESP8266Flasher.exe”) and set up the following firmware files at the addresses indicated on the “Config” tab:

File NameMemory AddressDescription
user1.bin0x01000ESP-Link Firmware v3.0.14
esp_init_data_default.bin0x3FC000Expressif Default BIN
blank.bin0x3FE000Blank WiFi Settings

The numbers are memory addresses so do be careful and don’t select the wrong one. At best things will not work. At worst you will brick your card.

If you are curious about the “Advanced” tab, I did not make any changes. The settings were:

Setting NameSetting
Baud Rate230400
Flash Size4MByte
Flash Speed40MHz

On the “Operation” tab, select the proper COM port, then click “Flash”.

When complete, go ahead and close the programmer, unplug the card, and set the switches to connect the CH340 to the ATmega328 (upload sketch to the ATmega328):

Switch NumberPosition
8 (Do Not Use)Off

Now flash the BrewPi Remix firmware with whatever tool you like. I just plugged it into my Pi and used “sudo /home/brewpi/tools/” since that script downloads the latest firmware automatically. In theory this board will allow flashing the ATmega328 over the air, I’ve just not tried that yet. Once you have the BrewPi firmware loaded, unplug and set the switches to connect the ESP8266 to the ATmega328 (serial bridge mode):

Switch NumberPosition
8 (Do Not Use)Off

Power the board up separate from your PC or Pi. Now from your computer, phone, or whatever; search for the access point created by the board. It will be something like ESP_XXXXXX. Connect to it, no password needed. Open your web browser and navigate to After a moment the esp-link page will show up. Go to the “WiFi Station” tab, and follow along. Click the link under “WiFi State” to switch to STA+AP Mode:

Select your desired wireless network (if they do not show up, refresh the page) and provide the proper password. When done click the Connect! button:

After it connects successfully, record the WiFi IP Address under “WiFi State.” For the purposes of demonstration, we’ll assume it’s

Now connect your PC to your normal network and connect to the board again via it’s new address ( Go to the µC Console tab and set the following:

  • Switch Baud Rate to 57600
  • Click the Reset µC button to commit the change.

Now press the MCU RESET button on the controller (or simply power-cycle by pulling the plug.) If you left it on the µC Console tab, you should see json from the controller in the console window after reset is complete. Success!

The last step is to configure your BrewPi instance for the controller. Assuming you are using a custom config (config.cfg), change the port to point to your board’s IP address and port 23 like this:

scriptPath = /home/brewpi
wwwPath = /var/www/html
port = socket://

This will work on all versions of BrewPi Remix starting with Changes to the python scripts would be necessary to use this with Legacy BrewPi. Re-start your script and you should be connected via WiFi!

One thing I came across which requires a small hardware change: If you are using one of @CadiBrewer’s shields with the LCD you will notice that the LCD does not work. This is because the shield attempts to separate the power for the shift register and LCD from the rest of the board by taking power off the ICSP header. This header does not line up with the ICSP header on the combo board. So, you must jumper 5 volts and a ground (+5V and GND) off the header on the shield to the ICSP header on the shield and all will be well.

Obviously this shows the Arduino and not the shield, but the headers are all in the same place.

Raspberry Pi Wireless Connectivity

The Raspberry Pi is an awesome little platform with uses from education to home automation. If you rely upon it to host a process or application wirelessly, you will sooner or later find it unavailable on the network. If you search the Internet you’ll find several “solutions”, some work a little, some not at all.

I’ve developed a script and a process to keep it running which will shut off power management for the wireless adapter and try to ping the gateway on interval. If the ping fails for a certain number of times, it will reset the adapter. If it continues to fail it can (optionally) reboot the Pi.

Install with the following command:

curl -L | sudo bash

If you wish to enable the reboot function, edit these lines:

# Reboot on failure

Add change to:

# Reboot on failure

After that change, reboot, or restart the daemon with the following command:

sudo systemctl restart wificheck

The git repository may be found here.

BrewPi Hardware

There’s two very important points I need to share about this:

  • Without the start FuzzeWuzze gave us on the “Mega Thread” on, a lot of us would never have successfully made our first rig. The first post is dated, the thread incredibly long (but still full of AWESOME info), the various fan Wiki’s also dated, so I wanted to persist for as long as I could how a person can put together the hardware
  • There are as many ways to do this as there are people doing it. This is ONE WAY it can be done. If you are smart enough to deviate from this, you should be smart enough to figure it out yourself. Please don’t ask me why your new idea doesn’t work

This post will share how to put the hardware supporting BrewPi together in the most basic way with which I believe a person can be successful. It is not meant to be “production ready”, it’s meant to show how it works on the bench so that the DIYer can add a case, etc., and use it on their fermentation chamber.

What you need

I’m not going to suggest which ones of these to buy, but I will give you some pictures that, along with the name/description, should be about all you need to find them on the Internet. I’ll give you a hint: I got all of these pictures except for the thermowell off Amazon. For the thermowell, seek out Brewers Hardware:

A fridge that you can “hack”. This can be as simple as keeping a fridge’s thermostat all the way on cold and plugging it into the system so that it only turns on by the BrewPi system. Most modern refrigerators use timers and such which make using them a little less straightforward. If you have what is commonly sold as a “kegerator”, it will work pretty well as it lacks auto-defrost, etc. This article will not detail how to hack a fridge (maybe some future article will), it will assume you are using one of those “kegerator” style boxes.

A working Raspberry Pi. This article will not detail how to setup the Raspberry Pi, nor address the software part of the build – that’s done elsewhere.

An Arduino Uno. I recommend not trying to get the cheapest one possible straight from China, and until you know why; avoid the ones that state they have a “CH340”. You can get a genuine Arduino Uno R3 on Amazon for $20, and decent clones for about $11. Get a USB A to B cable while you are at it if it does not come with one.

A 2-channel 5-volt relay, commonly the “SainSmart 2-Channel Relay Module” or a similar model.

A 15A 115v electrical outlet (if you are not in North America, modify this accordingly).

A “euro-style” wire connector strip, three stations will be needed. You can do this with anything, a breadboard, wire nuts, go wild. The first time I made this, this is what I used and it worked well.

One 4.7k Ω 1/4 watt axial resistor (sometimres you see this called a 4k7 Ω ). You are unlikely to find a single of these for purchase, they are pennies a piece. Pretty much anything you find that says 4.7k Ω 1/4 watt that looks remotely like the ones on the left will be fine.

Some 22 gauge Dupont jumper wires in male to female and male to male. You can generally get an assortment of gender combinations in various colors for a few bucks.

Some 16 or 18 gauge stranded wire, in black and red. You won’t need much of this, maybe a foot each. You can even cannibalize some from the next item.

A 16 or 18 gauge (16/3 or 18/3) grounded power cord. An old computer cord is a pretty good item for this if you have one.

(Optional) a “Ceramic Heat Emitter” in 60 or 75 Watts, commonly sold as a reptile heater bulb. Many indoor implementations will never need a heater, but if you have this in an unheated garage or shed in a cold climate, some form of heating will be required. Some folks have used a “personal heater” but even 100w is pretty hefty for this application – a light bulb is enough heat but you don’t want light in the chamber to prevent skunking your beer.

You’ll also need a lamp/cord/receptacle to support a lamp inside the fridge (if you decide to use one.)

(Optional) a small “personal sized” fan for inside the fridge to eliminate dead spots. Nothing large, whatever you have and will fit will work.

At least two DS18B20 sensors (called “one-wire”). Getting “waterproof” sensors with leads is important. Make sure they are directly powered and not parasitic. Searching the reviews and/or BrewPi threads will help you get known good items. Also make note of the wiring/color scheme from the manufacturer. You will need this. It’s nearly always listed with the item’s description.

(Optional but HIGHLY recommended) a stainless-steel thermowell. You won’t need this for bench-testing this of course, but using a thermowell for the “beer” sensor is much better than any of the other methods for getting a good beer temp. Make sure the sensors fit in the well.

Putting it Together

I could blather on about how to put this together, but I think a picture is worth a thousand words. This is a diagram done by 100Amps on Homebrewtalk that suffices for those 1000 words:

Arduino Electrical Connections

There are few things that while clear on this diagram I have managed to screw them up or allowed them to confuse me (or allowed me to confuse myself):

  • You can tie all of the One-Wire sensors together as shown since they are digital and have their own internal addresses
  • The “data” leg of the one-wire sensors go to the A4 terminal on the Arduino, power the terminal marked “5v” and the ground to “GND”. Each manufacturer of the sensors seems to change the colors around, so you will have to refer to the manufacturer for which color is which
  • A one-wire sensor (or many of them tied together) requires a single 4.7k Ω resistor between power and data in order to function correctly. This is called a “pull-up resistor” if you want to Google it. It looks strange but it’s necessary
  • There is a jumper on the hot side of the outlet that can be broken off with a pair of pliers which allows them to be powered separately – we use this to independently turn on and off the heat and cool

Step by Step Wiring

Refer to the wiring image above as you go through these instructions. The colors need not be the same, but if you keep them consistent you will thank yourself for it later. Print the pic (in color) to make it even easier to reference as you follow along.

Low Voltage Wiring

  1. Get your Raspberry Pi running, get logged in, play with it if you want. You can follow these instructions in the Raspberry Pi pages. You need not make it headless, do it however you want. The videos on the Raspberry Pi website are really good as well. All you need is the Raspberry Pi running, and able to connect to the Internet.
  2. Connect your Arduino to your Raspberry Pi with a USB A to B cable. This serves for both communications and power. Nothing will really happen yet other than an LED lighting up on the Arduino.
  3. Install BrewPi Remix just to make sure your primary pieces are working correctly. Doing it now avoids any confusion later on when you add the rest of the wiring. You’ll know it works before you end up adding more “stuff.” When you are done, the screen will tell you the URL you may use to access your new BrewPi installation. Open it up in a web browser and enjoy it for a moment! When you are satisfied it works enough to open up the page, you can come back here and worry about the rest of the hardware.
  4. Unplug your Arduino from your Raspberry Pi (you do not need to power down the Raspberry Pi first) before you proceed.
  5. You are now going to use your Dupont wires. Grab three different colors of your male to male wires and plug one each in the Arduino’s 5V, GND and A4 (this is your “data” port). These are all on the same side of the Arduino, on the same side as the black power inlet. Pick separate terminals on your Euro-connector, whichever ones you like, and run them there. No need to tighten things up right now.
  6. Take a couple of Dupont wires, male to female, which match your 5v and GND wires. Put the male ends into the corresponding Euro-connector terminals (obviously easier here if you use the same colors as your first two wires.) Again, just snug, no need to tighten.
  7. Take your 4.7k Ω 1/4 watt resistor and connect it between your A4 (data) connector and your power (5V) connector.
  8. You should now have two wires coming into the ground (GND) terminal, two wires plus one side of the resistor into your power (5V) terminal, and one wire plus the other end of the resistor into your data terminal (A4). You can snug them down now if you wish.
  9. Now take at least one (I recommend two) of your temp sensors and referencing the manufacturer’s layout, connect all of the ground leads into the other side of the GND terminal. Connect all of the power leads (may be referenced as VCC) to the other side of the power (5V) terminal. Connect all of the data leads to the other side of the data (A4) terminal. One sensor will be your “beer” sensor and the other the “chamber” sensor.
  10. Now you will connect your 2-channel relay. Take a look at the low-voltage side first. It will have two small male pin strips; one three pins and one four. The three pin strip should have a jumper (probably a small blue or black cap) between JD-VCC and VCC on the strip of three pins. This allows the relay to be powered by the Arduino.
  11. Now you will connect your leads from power (5V) and ground (GND) out of the terminal block to the relay. 5V goes to VCC, GND goes to GND.
  12. Take two more Dupont jumpers, male to female, of differing colors. These will represent heat and cool so maybe blue and orange would be good. Connect one to digital pin 5 and one to digital pin 6 (likely marked ~5 and ~6) on the opposite side of the other connections (USB connector side). At this point it doesn’t matter which is which, you will be able to set the pins later.
  13. The other ends of these jumpers will go to the IN1 and IN2 terminals on the 4-pin strip on the relay.

Your low-voltage wiring is now complete. You can go ahead and plug your Arduino back into your Pi. Refer to the instructions to set up your probes and relay pins and get to know your system. Experiment and test now before proceeding. I recommend a digital multi-meter to test the continuity at the high-voltage side of the relays so you can get the hang of how things work before actually applying high voltage. You can also view the LEDs on the relay card.

There’s nothing about any of the low voltage we’ve done so far which will be harmful to you. You might short some of the circuit logic if you are careless and allow things to touch each other, but I’ve had a lot of these systems laying around, in my lap, on a coffee table, even laying on the carpet, while I test.

High Voltage Wiring

This is where you can destroy your equipment, home wiring, start a fire, harm or kill yourself. BE CAREFUL and if you do not understand what you are doing find someone to help. This is something most home brewers will find trivial, but if there’s any doubt; don’t.

  1. Look at the “hot” side of your outlet. On North American outlets with the ground terminal towards the bottom, this will be on the right side of the outlet between the two terminals. These terminals are generally gold. There is a jumper there which you can grab with a pair of pliers and break off. Do so. This allows you to power each outlet separately, one for heat and one for cool. If you do not do this, you will be running your heater and your fridge at the same time and wondering WTH is going on.

    This is called a “split receptacle” or sometimes a “switched receptacle.” When you buy your outlet at the local big box store, the people that work in electrical (if you can ever find one) can point this out for you as well.
  2. Take two lengths of stranded wire, 16-18 gauge and preferably red. These will go between the relays and the outlet so maybe a foot or two long. Some crimp-on terminals (called “spade” connectors) would help here but are not absolutely necessary. If you do not use spade terminals, it would be better to use solid core wire for this part. Connect them one each to the hot terminals on the side of the outlet (where you broke off the jumper.)
  3. Connect the other ends of those wires to the “NO” (this doesn’t mean “don’t do it”, it means “Normally Open”) side of the two terminal blocks on the high-voltage side of the relay board. I’d recommend crimping on what’s called “bootlace ferrules” or tinning the ends of the wire (melting solder on the end) if you are using stranded wire. You can do without the ferrule or tinning for testing, but for production use, it’s highly recommended.
  4. Take a piece of black stranded (tinned or ferrules on the ends) or solid-core wire and run it between the NC (Normally Closed) terminal of relay number one (on the top as you look at the relay board with the high-voltage on the right) and the COM terminal on relay number two. Refer to the diagram above for clarification.
  5. Take your power cord and strip enough of the main insulation to work with the three leads. Strip the tips of the three leads. A spade terminal would be good on the ground (green) and the common/neutral (white) leads. The hot lead (normally black) should get tinned or a ferrule.
  6. Connect the ground to the ground lug on the outlet. Connect the common/neutral lead to the neutral side of the outlet.
  7. Run the hot lead from the power cord to the COM terminal on relay number one.
  8. If you are using a metal box for your outlet, run an additional (preferably green) lead between the ground lug on the outlet to the ground lug on the box.

At this point your high voltage side is complete, at least enough for testing. Test BEFORE you plug in your power cord! I am not responsible for anything that goes wrong here so make sure you know what you are doing or have a licensed electrician do the work or check your work. One outlet is going to be controlled for heat, one for cool. Your (optional) fan can be plugged in any convenient outlet – it should run 100% of the time.

I’d highly recommend you mount the outlet to something that’s not going to move, put it in an outlet box, something to protect you and your belongings from the high voltage terminals.

As one final step before plugging in your refrigerator or heater, grab a couple of cheap outlet testers with lights, or even a couple of table lamps, and test some more to make sure things work like you expect.

Work Complete

The work above, and putting the “guts” into a suitable box, are all I did for my fermentation chambers. I plug my kegerator (set on 100% cold) into the “cool” outlet, and my heater (a 60w lightbulb in a paint can) in the “heat” outlet, and let magic happen.

From here there are many ways to go … 3-D printed cases are getting pretty popular. I’ve also seen folks come up with really nice setups from just a trip to the big-box hardware store. The sky is the limit!

“Hacking a Fridge”

This sort of setup relies on being able to directly turn on and off the compressor on the refrigerator. Normal modern fridges often are “frost free” which is accomplished by using a timer and a small heater on the coils to defrost the tubes. It should be obvious that this would not work well for this application. As described here we use what ends up being a “switched power cord” and leaving the fridge wiring intact. There are MUCH more elaborate ways to do this. One of the best write-ups is on the original BrewPi website under Fridge Hacking Guide.

If you do follow the instructions here, you will need a way to get the wiring for the sensors, heater and fan inside the fridge. These methods range from obvious (a kegerator has a hole on the top for the beer lines which may be used for our purposes) to the exceedingly elaborate (some people drill through the sides and use surface-mount electrical connectors.) If you do drill your fridge, make sure you know where the coolant lines are. Piercing one of these is a one-way ticket to the junkyard.

For the Masochists (or the truly paranoid)

(This article is written for BrewPi Legacy Remix version, it likely applies to other versions but there may be some differences.)

You’re here for one of a few reasons:

  • You’re just curious about how things work
  • You hate easy things and want to do this the most difficult way possible
  • You are exceeding (perhaps justifiably) paranoid and refuse to run scrips as root. Maybe starting at the bottom of this article is a good place to start?
  • You are one of those people that find some twisted satisfaction in running something named BrewPi on something other than a Raspberry Pi

We’re not here to judge (or am I silently judging you right now?), we’re just here to help. Just like the government. Here’s what you have to go through to replicate most of the scripting in the BPR tool set. Note that this only addresses a single-chamber setup. I’m not sure I feel like describing what has to be done to do multi-chamber but a smart person can figure it out from the information that’s out there for the Legacy BrewPi.

Finally before we dig in, these instructions are written for Debian-based Linux distributions (of which Raspbian is one.) If you use something else, chances are you already understand the differences.


The bootstrap especially does some checking which may not specifically be strictly required, but is highly recommended:

  • Check to see if the default password of ‘raspberry’ is still current for the ‘pi’ user. If so, prompt to change it.
  • Prompt to set the proper timezone. Since BrewPi works on schedules and the graph is of course time-based, having the proper system time is important. Yes, I could do some work to allow UTC and display in the user time zone … but why?
  • If the hostname is still ‘raspberrypi’, prompt to change it. More than a few folks have more than one Raspberry Pi, and being able to use a nice name like “brewpi.local” to get to the system is handy. Plus, you should never have two machines with the same name on the same network segment. It confuses anything with an ARP table (like your router.)

APT Repositories

Manipulation of APT repositories is required to support this product. This obviously needs to be done as root, however the repos are GPG signed so in theory there’s an added level of security.

As with any other apt packages, it is always good practice to refresh your local apt indexes before doing any installs, updates, or uninstalls. This command will re-synchronize the package index files from their sources. The indexes of available packages are fetched from the location(s) specified in /etc/apt/sources.list.

sudo apt update

There are some packages known to conflict with the solution as well; namely nginx and anything related to php5. This should not be a surprise since we use apache2 as a web server and nginx is a web server itself. Yes a crafty person can make them coexist, if you’re that crafty you don’t need my tutorials. Some of the packages I suggest to reinstall will be reinstalled again with apache2 and that’s fine. The process may also suggest removing other packages which are included by dependency; remove those as well. To uninstall nginx, use the following command:

sudo apt remove libgd-tools, fcgiwrap, nginx-doc, ssl-cert, fontconfig-config, fonts-dejavu-core, libfontconfig1, libgd3, libjbig0, libnginx-mod-http-auth-pam, libnginx-mod-http-dav-ext, libnginx-mod-http-echo, libnginx-mod-http-geoip, libnginx-mod-http-image-filter, libnginx-mod-http-subs-filter, libnginx-mod-http-upstream-fair, libnginx-mod-http-xslt-filter, libnginx-mod-mail, libnginx-mod-stream, libtiff5, libwebp6, libxpm4, libxslt1.1, nginx, nginx-common, nginx-full

To uninstall php5, I could give you a script but you’re here because you either don’t trust my scripts or you can’t use them for some reason. You can use the following command to find php5 packages which may be installed:

dpkg --get-selections | awk '{ print $1 }' | grep 'php5'

You would have to uninstall each of the returned package names with:

sudo apt remove {package name}

Now you need to install a series of APT repos. Here’s the command you would run to install all repos used in this product:

sudo apt get git arduino-core git-core pastebinit build-essential apache2 libapache2-mod-php php-cli php-common php-cgi php php-mbstring python-dev python-pip python-configobj php-xml

Pip Installs Packages (pip)

In addition to the apt packages, several additional python packages will be necessary. These are installed with pip:

 sudo pip install pyserial psutil simplejson configobj gitpython --upgrade 

User Setup

BrewPi runs as its own (now passwordless) user. Here we create the brewpi user and add it to the dialout, sudo and www-data groups:

useradd brewpi -m -G dialout,sudo,www-data

Next we add the ‘pi’ user (or whatever user you normally use to the www-data and brewpi groups:

usermod -a -G www-data,brewpi pi

Clone git Repositories

There’s four repositories that make up this product:

  • BrewPi-Tools-Remix – The toolset that this article replaces, so we won’t clone it here
  • BrewPi-Script-Remix – The core Python scripts which communicate with the Arduino and website
  • BrewPi-WWW-Remix – The PHP website which forms the user interface
  • BrewPi-Firmware-Remix – This repository does not need to be cloned, one need only download the current compiled firmware

Make sure the /home/brewpi directory exists and is empty. Clone the scripts as the brewpi user with the following command:

sudo -u brewpi git clone -b master --single-branch /home/brewpi

The web root should be /var/www/html but new versions may change that. Clean out that directory (it probably has a default index.html file there) and clone the website as the www-data user with the following command:

sudo -u www-data git clone -b master --single-branch /var/www/html 

Set Permissions

One of the more common solutions to a whole slew of issues is setting the permissions correctly. There is a script for this in:


If you are still needing or wanting to proceed manually, the following commands are issued:

chown -R www-data:www-data /var/www/html
find /var/www/html -type d -exec chmod 2770 {} \;
find /var/www/html -type f -exec chmod 640 {} \;
find /var/www/html/data -type f -exec chmod 660 {} \;
find /var/www/html -type f -name ".json" -exec chmod 660 {} \;
chown -R brewpi:brewpi /home/brewpi
find /home/brewpi -type d -exec chmod 775 {} \;
find /home/brewpi -type f -exec chmod 660 {} \;
find /home/brewpi -type f -regex "..(py|sh)" -exec chmod 770 {} \;
find /home/brewpi/logs -type f -iname "*.txt" -exec chmod 777 {} \;
find /home/brewpi/settings -type f -exec chmod 664 {} \;

Arduino Firmware

You can download the precompiled firmware (sorry, not going to go into how to compile it on your own here) from the GitHub repo. For instance here’s how to download the latest Arduino Uno firmware:

curl -O

You would now flash your connected Arduino with the following command. Be sure to update the port (following the ‘-P’) with the port where your Arduino resides:

avrdude -F -e -p atmega328p -c arduino -b 115200 -P /dev/ttyACM1 -U flash:w:"brewpi-arduino-uno-revC-0_2_10.hex" -C /usr/share/arduino/hardware/tools/avrdude.con

Daemon Unit Files

BrewPi and a checker for the WiFi connection run as a systemd daemon. The following files must be placed in the /etc/systemd/system directory. The first is named brewpi.service and contains the following text:

Description=BrewPi service for: brewpi

ExecStart=/bin/bash /home/brewpi/utils/ -d


Change permissions on the file, enable and start the service with the following commands:

sudo chown root:root /etc/systemd/system/brewpi.service
sudo sudo chmod 0644 /etc/systemd/system/brewpi.service
sudo systemctl daemon-reload
sudo systemctl enable brewpi
sudo systemctl start brewpi

The (optional) WiFi check file should be saved as wificheck.service and it contains:

Description=BrewPi service for: wificheck
ExecStart=/bin/bash /home/brewpi/utils/ -d

And as with the brewpi daemon, set permissions, install and start it with the following commands:

sudo chown root:root /etc/systemd/system/wificheck.service
sudo sudo chmod 0644 /etc/systemd/system/wificheck.service
sudo systemctl daemon-reload
sudo systemctl enable wificheck
sudo systemctl start wificheck

Work Complete & Final Thoughts

In theory, you should now have a working BrewPi Remix running in single chamber mode. I will however leave you with some final thoughts.

If you are one of those folks who got here and followed these instructions out of some sense of increased security by not running my install scripts I’ve got bad news for you. You are still running scripts from some random person on the Internet and some start as root.

With thanks to the folks at, I’m going to paraphrase a few of their sentences:

Using curl|bash or curl|sudo bash certainly seems insecure. To anyone with a basic understanding of Unix, the construction makes it really obvious: This command will give the named web site direct access to your system, with the ability to do anything that you could do. This feels very wrong: We should be able to install software without giving the developers full access to our systems, right?

I would be the first to agree that software you install should not be automatically fully trusted. Unfortunately, however, traditional Unix software is always granted the full authority of the user who runs it (and in the case of a stock Raspbian OS this implies passwordless sudo). When you install software on Linux, no matter what package manager you use, you are giving that software permission to act as you. Most package managers will even execute scripts from the package at install time – as root. So in reality, although curl|bash looks scary, it’s really just laying bare the reality that applies to every popular package manager out there: anything you install can pwn you.

If you wish to install any software without giving it full access to your system, you must install it on a dedicated machine, VM, or (perhaps, with caveats) an isolated user account. In truth it’s more work than a lot of people want to deal with and in my experience people spend a lot more time complaining about it than actually taking steps to be secure.

The reality is this:

  • This is free software and you are invited to not run it if you are that concerned. I’d argue however that even the most paranoid among you have downloaded and run applications from the Internet with no additional security. At best, maybe you scanned it for viruses, but I’d be willing to bet a normal home user would not perform a source-code scan. If you are a person who really does a source-code scan, this is all written in bash, PHP, Python and the firmware in a proprietary C-ish language. It’s all there and all able to be downloaded freely and handled however you wish under the terms of the GNU General Public License.
  • This is intended to be run on dedicated hardware. A Raspberry Pi is really perfect for this and a Pi Zero W is about $20. There’s no reason to try to run this on some other rig on which you do other things that could be compromised by rogue code.
  • The last significant vector at risk here is the network to which the BrewPi machine is attached. If you have IoT devices, surely you have a separate wireless LAN segment for them? Put this there. Tom has a great article about IoT security. You can also choose to not have your BrewPi connected to your home network at all. Sure you lose some functionality, but you can always disconnect the network and just use it with a local keyboard, mouse and monitor.

I’m not making fun of people displaying a healthy dose of paranoia. At last count I am tracking 552 website credential pairs, all using unique highly complex passwords. Yes that’s right, I have over 500 passwords to keep track of. In addition I use two-factor whenever possible. Believe me when I say I am a fan of security. Sometimes though you gotta pick your fights and mitigate risk when you do.

One last word: As a fan of security I do have several ideas how to make this application more secure. I don’t have a schedule and nobody is paying for this so who knows what I’ll get done. Stay tuned though, surely the battle will be won in small skirmishes.