Multi Scale System - How to use mutiple scales

Support
1

Hi I need some help with my scale system. I’ve created all the main components for my system, I’m just trying to get this work for the code side now. I did use chatGPT to develop Code for this I’m using the Maker verse hx710b load cell amplifiers.
I don’t know whether their are any issues within the code or hardware.

I started of by verifying that each 4 of my scales works correctly individually. Then I started to mess around with Two which I could not seem to get working e.g. scale 1 reports 1360g and scale 2 reports 0g, when I apply 200g load to scale 1 nothing happens, but when i apply it to scale 2 > scale 1 reports 1160g, Scale 2 reports 200g.

I want the system to function like this kind of https://grassrootsmotorsports.com/forum/grm/diy-arduino-corner-weights/186240/page1/ but on a smaller scale products no larger than 10kg and digital so I can intergrate it into a web UI.

Issues I think could be causing (not really sure new to this):

  • Interference of by using the same power source, as I am using the same 3V3 and GND for all
  • Use HX711 Load Cell Amplifiers Instead
  • Use A multiplexer
  • Issue within the code

Components I have on hand:
Computing Device:

  • Windows & Mac Computers
  • 1x Raspberry Pi Pico W
  • 1x Raspberry Pi Zero W

Load Cell:

  • 4x 10kg Beam Load Cell
  • 4x 50kg Half-bridge Load Cell’s
  • 4x 5kg Half-bridge Load Cell
  • 5x Makerverse Load Cell Amplifier
  • 1x HX711 Load Cell Amplifier

Wiring and Power:

  • 830 tie point breadboard
  • 1x 2-AA Battery Holder
  • 1x Hook-up Stranded Wire - Red (22 AWG)
  • 1x Hook-up Stranded Wire - Black (22 AWG)
  • 1x Hook-up Stranded Wire - White (22 AWG)
  • 1x Hook-up Solid Wire - Yellow (22 AWG)
  • 1x Jumper Wire 20cm Ribbon (M/F, 40pcs)
  • 1x Jumper Wire 20cm Ribbon (M/M, 40pcs)
  • 1x Jumper Wire 20cm Ribbon (F/F, 40pcs)
  • 1x SparkFun Multiplexer 8 Channel

Current System

1
11920×1607 317 KB

Current Diagram

2
21280×720 113 KB

Thank you,

1 Like
2

Hey Ashton,

Seems like you are so close to being at a good point with this project! From what I can see with the error, its likely that there is something in the code that may be getting some signals crossed, or the calibration of the load cells is a bit off. For all those load cell plates, have they all been calibrated for offsets that naturally come with each cell? Are you attempting to make them hot swappable, as those bunches of different load cells will likely require different calibrations that would need to be included in your code and a way of recognising the swap between them?

Seems like you are so close though and we would love to see how it turns out!

Cheers,
Blayden

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3

If you arrange the possible issues based on likellihood and ease of testing, I would put the power supply at the top of the list. Get a separate 3.3V supply for the scales (and the amplifiers if you use them). Make sure the grounds from the two supplies are connected so everything shares a common ground.

Second is poor connections, especially on the breadboard. Make sure everything is tight and clean.

The software would come next. Trim your program down to the absolute minimum and go through it step by step. Add a big bunch of debugging statements. If you still can’t see an issue post the code for someone else to look at - a second set of eyes will often make all the difference.

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