It got me thinking, is this something that has ever been considered to integrate into Brewblox? It would be great to be able to monitor this on the same Brewblox controller screen rather than having extra screens and logging would be fantastic.
The HX711 amplifier chip appears to be a custom protocol with 1 data line and 1 clock line so may need an interface board to utilise the RS422 on the Spark controller (I assume there is currently no software in the Spark to support this interface yet though).
That solution uses a Wemos D1 mini (ESP8266), configured via ESPHome and attached to Home Assistant. I followed some instructions in the BrewBlox docs to expose the block data to Home Asssistant. My plan is to create a nice dashboard for monitoring brewing and fermentation activities on a wall mounted tablet running Home Assistant - and at that point, it would be trivial to add the keg scale stuff to the same dashboard. FWIW.
Following this; I’m looking at scales for under my all-in-one kettle with the hope I can use it to control a solenoid for water in and pump control for out.
For now I’m using a Pi Zero W and Node-Red with relays via MQTT, so was looking at a serial connection to the scales. However I’m considering building my own (scales) due to the price of the models that are the right size. If I can reuse the components once I go to a Spark board, that’d be sweet.
The large peak is the hex bit, which I think is about 6g. The small peaks are the coffee bean, which google tells me is 132 milligram.
So it looks like I can also measure load cells accurately with this new board.
For monitoring kegs though, I would like to investigate an alternative. If you measure the head pressure in the keg, I think you can calculate the head space from the pressure drop and how quickly it goes back up could after a pour.
Perhaps when combined with controlling a valve for the CO2 to the keg, you could put the regulator higher than the desired head pressure and with the valve control the head pressure.
This allows you to adjust the head pressure to the temperature. I think you can also dissolve CO2 quicker by measuring how quickly it dissolves and put CO2 into the keg in bursts.
I hope that in the CO2 line near the keg would be enough. The regular limits the inflow, so I think the line pressure between regular and keg is equal to the headspace pressure. Not much resistance there I assume.
I ordered some of those same load cells to give it a try. Not with the HX711, but with my own board. Then I can also measure the total bridge resistance and do temperature compensation with that.
Just pretty standard M4 inserts. I drilled out to 5mm and then melted them in.
I found a weakness in the feet. The point load of the load cells easily dents the printed parts when I put my full weight on the scale. And then the legs are not equal and the scale will wobble.
Looked for a sheet metal piece to fix that and ended up using some break-off knives for that.
