It works well, except what I’m measuring has 12 legs, and so 12 total load cells giving a single weight reading would be better. I think I can hook up 12 load cells to 3 hx711s connected to a single ESP32, but I’d really prefer if they were a single reading in ESPHome so that the calibrate_linear filter could be used on the entire system, and not on 3 independent measurements.
Is it possible to combine the signal from 12 load cells into something that can be read by a single hx711? If not, does anyone have any suggestions for how I can set this up with the constraint that I can’t really calibrate the 3 different sets of 4 load sensors independently?
I dont think those can be daisy chained. You can use multiple hx711 IC’s to make 12 load cells and easily combine it all into 1 template sensor. If you have the free gpios, thats probably your simplest way to go.
Youd just need to put it in a lambda like hx711a + hxz11b + hx711c / 3 = the average… or whatever calculation you need to do and then that template sensor will now show the sum of all 12 load cells.
Thanks, but I’m trying to avoid having to add the weights because I just don’t see how I would calibrate the 3 independent hx711s one at a time. It’s not possible to only put a weight on 1 of them and not the others.
I dont even know what it is your doing or what has 12 legs but, i can confidently say that it is very possible. It only becomes less doable if you dont project confidence in yourself and start a project with the mindset where “cant do it” is acceptable or decide things are to hard and and cant be done before you even try!
Change your mindset to, " im going to kick this projects @$$!" And not a mindset of, " its too hard, this way is easier but, i might fail anyway so who cares"
Its also a good idea to be open to the possibility of being wrong. So many times people want help help with some project but they decide what information is relevant to us they need “this information” but not the rest of it where we have an idea of what it your trying to do here.
Its not very helpful to yourself to limit what knowledge or information can come to you.
Paint a picture of the whole project in your question. Its actually much more helpful than people think.
What I’m trying to measure is bed weight. I currently have a single hx711 with 4 load sensors between the frame and mattress, and that works ok, but there is a large amount of fluctuation in the readings as people roll around. As a result, the system sometimes gets confused which person is in bed, or if it’s 1 or 2 people, etc.
A more accurate way to measure weight would require putting the sensors between two hard surfaces and placed so that the full weight of the bed must go through them. That’s where my requirement to use 12 load sensors comes from, as my frame has 12 legs.
If I calibrate the sensors independently then they will be measuring the full weight of the bed and people, rather than being able to tare them with the bed weight on them. I could subtract that bed weight in software, but in my experience these senors drift over time and need to be recalibrated, and I’m not going to remove them all from my bed frame to recalibrate.
That’s why it would be nice to have the same set up I do now, but just with 12 load sensors instead of 4 wired in such a way that whatever the hx711 is measuring electrically is the combination of the sensors.
For sure it’s doable, it’s common to use multiple parallel cells in industrial setups.
I’m not sure if it’s the easiest and most economic way to sense persons in bed.
I have doubts that beyond common wheatstone setup you can use $3 aliexpress components to archive better results.
