Open Source Espresso Scale

Want to talk espresso but not sure which forum? If so, this is the right one.

#1: Post by jousis »

Hello fellow makers, this post is mainly for you :)
I just released the first version of my scale project and you are welcome to contribute/fork/copy/sell, respecting the mentioned licenses.

Everything is open source, from schematics to the ionic mobile application.
The project is still in development but since I am not exactly a developer nor an EE, I will soon reach my limits.
I am currently searching for the best solution for touch buttons and will update the PCB in the upcoming weeks. So, don't rush to print it yet.

Of course you can propose/ask anything, I will do my best to explain.

Software features
Many, many, many options, from speed to filtering, 3 fully configurable timeouts (10s-2550s) for your special "auto-off" needs.
Calibration using ANY weight.
0, 1, 2 3+ decimal digits. Depending on the load cell you will choose you can measure from body weight to gold.
Auto tare (still fine tuning).
Rate of change (in grams/seconds - momentary)
more to come (timer, tare history)
BLE mobile application project (ionic)

ESP32 microcontroller with BLE and Wifi
ADS1232 ADC from Texas Instruments (not the usual HX711 project ;) )
Battery & USB powered (& charging)
Custom PCB with off the shelf components, nothing fancy or extraordinary but all of high quality. BOM included.
3d printed case (stl & fusion 360 project available)

More info and all the files available on gitlab

Except some parts which are taken from other open source projects (sparkfun esp32 thing, various libraries) the design is made from scratch.
The size and shape of the PCB might remind you that of the acaia lunar, because it is designed like exactly that. I wanted a drop in replacement of the one they have so I can finaly connect my scale (yes, I do own a lunar) to my espresso machine (has a micro controller also).
Their closed source, proprietary BLE API frustrated me so much I dedicated two months to develop ESPresso Scale. (they only recently released a proprietary API for only ios).
Dear X manufacturer ,don't be like them, support open source.
Open source helps the society and can still help your pocket (you can sell open source).
Or at least, don't use proprietary APIs for something so generic like BLE.
★★ Quite Helpful


#2: Post by happycat »


I built an IOT scale a few years ago... hx711, loadcell, ABS pipe...

My philosophy is to offload the interface to a wifi device so I had a scale that reported to a web interface with a take and weight button

Glad to see projects like this... I never did anything with mine after my prototype
LMWDP #603


#3: Post by jousis »

The best part about open source: it is open :D
Not too late to revisit your project. Copy some or all parts of my design/software and make your own version !

HX711 is crap. Forget about it. Check out ADS1232, your will fall in love.
You can buy breakout boards with 1231/1232 for testing before diving deep to your project.

Yes, it is more expensive, but it is that much better.


#4: Post by max »

I love seeing this type of project and am really looking forward to see what comes next!
jousis wrote:Dear X manufacturer ,don't be like them, support open source.
I have been wanting a fancier scale for a while and am waiting for manufacturer X do make it.

...unless I make one first with the help of your work. What, approximately, is the width?


#5: Post by jousis »

You can find all the schematics and layer photos on gitlab.
I have two pcb versions.

PRO is 97mm * 32mm ... pLayer.pdf

The other one with 7segment display is 99mm*32mm ... pLayer.pdf

I will update both PCBs soon with:
-4.7V excitation voltage for increased accuracy when powered from USB
-battery voltage monitoring (now it only warns you with a led)


#6: Post by max »

Thanks. In hindsight it seems obvious I should have checked in the "PCB Layers" directory instead of "PCB Images".

Hopefully I have more time for projects soon!


#7: Post by mammamia »

This is a fantastic project. And it is OPEN source for everyone. I respect people having mad skills and open mind like you. I personally like simple but reliable product like G-Shock DW-5000 watch. Plz keep Mil-Standard level waterproof in your mind before finalizing your awesome baby. What about a name of C-Shock(coffee shock), haha!


#8: Post by jousis »

It is easy to protect this design from water dripping from above.
a) Cut a small plexi glass piece exactly as the monitor cutout (depends on your version) and glue it. Then plasti dip the whole top with any color (not the plexti glass though, you need to see the display :D )
b) You can spray 3-4 layers of clear plasti-dip on the whole top surface, then mask the monitor and spray another 3-4 layers of any color plasti dip you like.
c) your idea here...

The top case "hugs" the bottom* so any water dripping won't get inside.
Even it it finds its way through, you have the schematics, find which component is fried and replace it !

nothing is obvious with my directory structure...I need to work on that. Sorry.

*to be fair, kudos to the "unnamed manufacturer with proprietary ble api" for the amazing case design.
I guarantee you others will copy it if the market opens up.


#9: Post by jousis »

Project is done, I now have a fully customizable and water resistant kitchen scale :D
I want to do some minor modifications on the firmware but currently everything works as is.
If you are building a scale there are a lot of snippets you might want to steal, check out gitlab.
Some screenshots from the app:
Image ImageImageImageImage


#10: Post by Elfmaze »

Not too familiar with github, but I know how to work a 3d printer and can muddle through Arduino programming and a soldering iron. Are you selling the completed PCB boards?