Keg Scale
Always know how much beer is in the keg! A scale system that display how many liters of beer you have left in each kegs. Just put it at the bottom of your kegerator and place your keg on it. The screen connects with ESPnow (no WIFI required) and can be placed anywhere.
This project is inspired from this tutorial.
Bill of Materials
The amount of scale kit, USB-C breakout board and USB-C cables depend on how many scales you plan to use.
This BOM assume you are using 5 scales in a kegerator and does not take into account the power in cable as it will depend on your setup.
- 2x ESP32 S2 Mini
- 5x HX711 Scale kit
- 6x USB-C 4pin breakout board
- 5x USB-C wire (30cm)
- 1x USB-C wire (1m)
- 1x ST7735 1.8" display
3D models
PCB
- KiCad project
Code
- ESP32 code
Tutorial
First, you need to decide if you are going to use one of the scale frame as the hub or if you want a dedicated hub. If you choose to use the dedicated hub, you won't need a "Hub scale frame".
Programing the ESP32 S2 Mini
If you need help setting up the environment for programming an ESP32, please refer to this tutorial
You will need to program the ESP32. It will be much easyer to program it before your begin. Download the arduino IDE projects from GitHub then upload it to the ESP32. Make sure you select "LOLIN S2 Mini" from the board list and upload the hub firmware to 1 ESP32 and the display firware to the other. Keep track of which on is which!
Here are some modifications you might want to do the the firmwares before uploading them:
Scale frame
Print or order the amount of frame you'll need.
Then prepare 1 USB-C breakout board like so:
Once done, install the probes and the USB-C port.
Now connect the probes wires in a specific way. Cut them to length and solder them. Remember to double check before cutting!
Once the probes are linked, solder the leads to the HX711 board.
Solder the USB-C wires to the HX711 board.
Secure the HX711 board to the frame
1 unit done! Do as many you need. For a maximum of 5 per hub.
Hub scale frame
Print or order the hub scale frame
Prepare 4 USB-C breakout board like so. Those are used to connect the scales to the hub
Prepare 1 USB-C breakout board like so. This will be the power input port.
Install the probes and the 5 USB-C port just like for the scales frames. Note that the power input port has a specific location.
Now connect the probes wires in a specific way. Cut them to length and solder them. Remember to double check before cutting!
Once the probes are wired, we must solder the leads to the HX711 board.
Now you need to connect everything to the ESP32. Make sure it is the one with the hub firmware on it. This is the brain of the device.
Your hub is ready!
Dedicated hub
Print or order the Hub case.
Prepare 4 USB-C breakout board like this. Those are used to connect the scales to the hub
Prepare 1 USB-C breakout board like that. This will be the power input port.
Now you need to connect everything to the ESP32. This is the brain of the device. Do it like so:
Your hub is ready!
Display
First, print or order the display case.
Then solder the required wires to the display. I suggest using the same colors I did to prevent errors.
Now solders the wires to the right pins on the ESP32. Make sure it is the one with the display firmware on it.
Secure the ESP32 to the enclosure
Install the top part of the enclosure This should be a snap fit.
You are done! Plug in everything and enjoy a nice cold beer. You deserve it. Cheers!