HX711

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mra2ko
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HX711

#1 Post by mra2ko » 19 May 2022, 19:35

Hello all,
I would like use weight sensor with HX711, so HX711 is still in testing progress ? Or in whitch firmware is possible found.
Thank !
Joe

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Ath
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Re: HX711

#2 Post by Ath » 19 May 2022, 20:20

According to the documentation, the HX711 load cell interface is included in the TEST_A builds.

As explained on this forum before, the TESTING moniker isn't actually a sign that the quality of the plugin isn't of production quality. It is of good quality, as there are close to never support requests for this plugin, indicating that it is very stable.

The TEST name is just kept to distinguish the later added plugins from what used to be the NORMAL set of (then stable) plugins, but the TEST sets all include that NORMAL set too. It's just the sheer number of plugins (and thus total size of the code) that prevents them from being included in a NORMAL set, but we have the MAX builds for that, though that can only be installed on an ESP32 that has 16MB flash on board. Even though there are ESP8266 that have 16MB flash, that CPU doesn't support the > 2MB bin size required to include all plugins, nor the RAM memory to manage all that.
Again because of the restrictions in bin size, the TEST set has been split into TEST_A..TEST_E, where a limited set of plugins, on top of the NORMAL set, is included in each TEST build.
/Ton (PayPal.me)

mra2ko
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Re: HX711

#3 Post by mra2ko » 19 May 2022, 21:37

Well, thank to reply, I test it... !
TNX

mra2ko
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Re: HX711

#4 Post by mra2ko » 26 May 2022, 17:29

Hi, anybody who can help me please with setup HX711 with 4 load cell to get real weight number out ?
I have all wired, I see numbers in device list, but nonsense numbers, still changing and I am not able get real output.

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Re: HX711

#5 Post by TD-er » 26 May 2022, 18:29

How are the load cells connected?
Sometimes it may also be a grounding issue (e.g. you need to connect E- to the GND of the board)
But you may need to check the datasheet for that.

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Re: HX711

#6 Post by mra2ko » 26 May 2022, 21:58

TD-er wrote: 26 May 2022, 18:29 How are the load cells connected?
Sometimes it may also be a grounding issue (e.g. you need to connect E- to the GND of the board)
But you may need to check the datasheet for that.
Cells are coneccted as is on the pic. With the stable load is output in device very unstable.
Výstřižek.JPG
Výstřižek.JPG (59.03 KiB) Viewed 2453 times
Thank to help!

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Re: HX711

#7 Post by TD-er » 27 May 2022, 00:39

The Sparkfun tutorial mentions the sensors must be placed at equal distances.
https://learn.sparkfun.com/tutorials/lo ... -guide/all

Found also this video which discusses your setup too: https://www.youtube.com/watch?v=LIuf2egMioA

Maybe you should also verify the resistance is as expected (and mentioned in the video) over the diagonals.
https://circuitjournal.com/50kg-load-cells-with-HX711

Here it is mentioned you really should connect it as in your diagram:
https://forum.arduino.cc/t/hx711-and-50 ... s/575398/4
Thus black wire to black, white to white and make sure to measure on the diagonals on the red wires.

Also see this topic: viewtopic.php?t=5499
(especially the last post)

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Re: HX711

#8 Post by mra2ko » 13 Jun 2022, 21:29

Now weight measure working ok, but...
Any exactly wiring for temperature compensate ?

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Re: HX711

#9 Post by TD-er » 13 Jun 2022, 21:48

What was needed to make weighing work?

And what do you mean by the temperature compensate?
I'm not aware of the HX711 being able to compensate internally for temperature.
Also I don't know what parts exactly cause a drift based on temperature changes.
I can imagine the metal rods inside the cells will expand based on temperature rising, so they may register some change in load.
But I don't know whether thats the only change, nor if it is fully linear.
Such metal rods may expand in more than one dimension and these cells may only register linearly in 1 dimension.

What you can do is add another one without any load on it (or a constand load) and see how this one changes while the temperature changes, so you can compensate for it.

mra2ko
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Re: HX711

#10 Post by mra2ko » 13 Jun 2022, 21:58

Load cells are temperature dependent, see bellow the graphs...
Load are still the same, when the temperature drops the weight also drops.
Can you pls post exact wire setup for next cell.
Thank !
2.JPG
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1.JPG
1.JPG (35.99 KiB) Viewed 2265 times

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Re: HX711

#11 Post by TD-er » 13 Jun 2022, 22:03

mra2ko wrote: 13 Jun 2022, 21:58 [...]
Can you pls post exact wire setup for next cell.
Nope, I can't.
Simply because I don't know it and have never tried it myself to compensate for it.
But I am very interested to see how it could be compensated for.

Did find this discussion, but not sure if that's the "magical" fix: https://electronics.stackexchange.com/q ... mpensation
Especially since there was no update on the thread and also not made clear how it has to be connected to a HX711 and which load cells should be used for measuring weight and which ones to be mechanically "floating"

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