Usbscale is a program that reads weight data from a USB scale. Compilation is very simple and should work on any system with libusb-1.0 and gcc.
You will need the development headers for libusb-1.0. Once you have that,
you simply need to run
make in the source directory. If you get a "permission
denied" error when running usbscale, you may need to configure udev on your
system to give permission to use the scale. The file 50-usb-scale.rules
contains a sample udev rule file that should be placed in
usbscale and it will automatically report on the first USB scale
that it finds. The weight will be output to
stdout, while any diagnostic or
error messages will be sent to
stderr. An exit code of 0 means that a scale
was found and a weight was successfully read. Any other error code indicates
that a weight reading was unavailable.
Zeroing the scale
There is somewhat-experimental support for sending a tare command to the scale.
You can invoke it by running
usbscale zero. Not all scales seem to do the
right thing when they receive this command, but please let us know whether your
scale works in the GitHub issues.
Adding support for more scales
By default, usbscale only supports a very limited number of USB scales. It does not search for just any USB scale, but only those listed in scales.h. To add support for another USB scale, it should be enough to add its vendor and product IDs to scales.h. In any case, you should contact me (see below) so that I can add your new scale to the main source code to benefit all users who may have the same scale.
The license for usbscale is the GPLv3, whose full text can be found in the
COPYING. This means that you can reproduce and redistribute this
software, as long as you provide any and all modifications that you have made
to the software available under the same license. Notably, you may not
integrate this software into another product without making the whole product
open source. This paragraph is not definitive; please read the license
Additional licensing terms may be negotiable.
If you have a code-related issue (bugs, patches, etc.), then you can create an issue on the usbscale Github repo. Otherwise, the best way to contact me is by sending mail to erjiang at indiana.edu.