Project for getting values from a Scale and driving a stepper motor to add powd

Hi,
I am very new in the Arduino world and want to start a project now where the Arduino would get a value (weight) from a small scale and then control a stepper motor to throw more powder onto the scale until the set value is reached.
What hardware would be required (which Arduino). Do I need drivers for the stepper motors.
How do I enter the required weight. Is it possible tp use a phone and Bluetooth or just a pc connected to the Arduino?

Thank you
Kind regards
Michael

Any of the Arduinos will do the job with the appropriate parts .

I’d suggest you buy a genuine UNO and play with it for a while before jumping in .

Get yourself a load cell and HX711 for the weighing and start there .

Hi Hammy,

thank you for the answer.
I already have a scale with RS232 output. Wanted to use that as input for the Arduino.

Is there also a display to connect to show the set value that is required?

The Data that is put out is as per attached picture. Need to get the data values.

Kind regards
Michael

Image from Reply #2 so we don't have to download it. See this Simple Image Posting Guide

...R

You cannot connect an RS232 output directly to an Arduino as the voltage levels are not compatible. You will need a MAX232 to convert to the Arduino's TTL serial voltage levels.

As far as receiving the data is concerned have a look at the second example in Serial Input Basics - simple reliable non-blocking ways to receive data.

You can certainly connect a display to an Arduino but I suggest that you start by displaying the values on the Arduino Serial Monitor.

It would be useful if you can post a diagram to show the proposed mechanical arrangement with the stepper motor. I wonder if a gravity-feed system with a simple means (maybe a servo) to interrupt the flow might be simpler.

...R
Stepper Motor Basics
Simple Stepper Code

Hi Robin,
thank you for all the information and links. It surely helps a lot.

Will order an Arduino and start playing.

The problem is that the powder has to be trickled very slowly on the scale and it is quite coarse (about 0.5mm x 1mm spheres) so blocking and unblocking with gravity feed and a servo would maybe be too inaccurate because as soon as it opens too much of the powder drops and closing could also be blocked.

Kind regards
Michael

gummi_:
The problem is that the powder has to be trickled very slowly on the scale and it is quite coarse (about 0.5mm x 1mm spheres) so blocking and unblocking with gravity feed and a servo would maybe be too inaccurate because as soon as it opens too much of the powder drops and closing could also be blocked.

Maybe an Archimedes screw ?

…R

Ammolytics has some pretty in depth stuff on their blog about doing this. The short answer is it's really simple, but you sort of have to know where to look for the information you need. There's also quite a bit of stuff over on the Accurateshooter forums from the early stages of the Autotrickler development. If you want to re-invent the wheel, though, I'm all for it. :slight_smile:

First of all, I'd pore over your manual for your scale and see what exactly you can do with it. The RS232 stuff is probably the only daunting part of all of this and that's all a matter of the quality of the documentation. You may be able to set target weights and whatnot directly on the scale. (Can be done with some A&D scales for sure.) You may only be able to pull data, in which case you simply need to be able to read it and format it in a way that you can compare it to a value.

If you want to get into bluetooth or wi-fi and apps and all that you'll have to research those aswell. That territory is very well covered, and since this project is really very simple at heart (Set a value A, read a value B, compare values A and B, output a simple on or off signal) almost any type of user interface can be made to work. Ammolytics might have a plug and play solution for this depending on your desired set-up and existing equipment.

As for the mechanical design part, I'd look at all the current electronic tricklers and figure out what route you want to go. They can be as simple as a 3 volt vibrating motor or as "complex" as a stepper or servo. (Neither are complex, but they are slightly more complex than a basic, two wire, DC motor.) You'll want a motor driver for any of them, but that's mostly to protect the board and to prevent noise. A cheap motor driver for a basic motor of sufficient size costs about a dollar or two.

I've actually been about as far down this particular rabbit hole as a person could get here in the last few months. I'm building a system around a 50 year old opto-mechanical analytical balance, though, so my solutions are going to be pretty different.

I have a small load cell scale and I can tell you that they’re not very good when little bits are added slowly.

I put a container on the scale, tare it, and add bits until the number is right. And then I pick up the container and let the scale show minus the tare weight and then put the container back on the scale and the number is usually higher.

Little bits below some delta-weight don’t get seen on the scale without some poking and resettling. Sometimes a tap is all that’s needed.