Interfacing a precision scale with a Raspberry Pi or a computer

The following code helps you interfacing a Raspberry Pi (or any computer really) with a precision scale and log the measurement values into a file.

Use the script

Log in

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If you're using a regular computer (not a Raspberry), go to the next step directly.

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If you're using a Raspberry Pi, you'll first have log onto it. If you don't have a screen + keyboard connected to your Raspberry, you can connect using another computer using an RJ45 (ethernet) cable and use SSH. To use SSH, open a terminal (on windows: Windows key + R, and then type powershell + Enter). If you didn't change the default name of the Raspberry, enter the following command:

ssh pi@raspberrypi.local

The default password is raspberry.

Clone or download

Download this project onto the computer (or Raspberry).

If you're using a Raspberry, are usually using Windows and are not familiar with Linux, you can download the project onto your Windows computer and use FileZilla to move the folder from your computer to the Raspberry.

Change directory

Open a terminal and cd into the project you just downloaded. For example if you put it onto the Documents folder you'll do:

cd Documents/precision_scale-raspberry_pi

Change the parameters

Open the file named parameters.yml and change the values of the connexion parameters according to the ones given by the manufacturer of the scale, or the one you parameterized onto your scale.

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Note

You can use Julia to know which serial port is used for the connexion. Simply execute this code and copy/paste the results into the portname value in parameters.yml:

using Pkg; Pkg.activate(".")
using SerialPorts
list_serialports()

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Run the script

Run the script into Julia:

julia monitor_weight.jl

If you're running the script onto a Raspberry-Pi, you probably want to use nohup so you can reconnect to the process afterward (no hang-up after disconnection). To do so, run the following command instead.

nohup julia monitor_weight.jl

That's it! Julia is now monitoring the data sent by the scale.

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Python dependency

If you want to avoid the Python dependency, use the branch named Using-LibSerialPort.jl-instead-of-SerialPorts.jl which uses LibSerialPort. This is far better but does not build on my Raspberry Pi (don't know why).