M5Scale / HX711 unit weight measurements inaccurate

  • Hello,
    We've been testing a weight unit recently, part of a M5Scale kit but connected directly to a M5Go, however it does not measure weight properly. We've tried with a few objects we know the weight of, and it was way off, under the real weight, and not consistently so. An object that weight 500g shows up at 268g, while a 100g object showed up at 71g.
    I read here that there may be a pre-calibration to do before hands, but how can we do this? We did the rest to 0 of course, but that's not it.

    Any thoughts? Thank you!

  • I dont have this unit, but if you look at the following github where I believe the library is used from there are calibration instructions there:


    I'd start with that and see what happens.

  • The HX711 and loadcell don't necessarily return a linear a value. It is more likely to be a curve.. the nature of materials.
    You can create a variable and factor all your read values by this amount. For example in your case 500/268 = 1.87... So assign this value to your variable and multiply you readings by this amount. This will be approximate and it will vary for different weight ranges but you can keep refining it until you are happy. You can extend this method over various weight ranges and write conditional statements to apply different corrections for different ranges. Or if you have the smarts you can write a formula for the curve and apply it to your read values.