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This library lets you read weight from a standard USB scale using pure PHP.

Could be ported to other languages with ease, should they haveunpack()

Tested with:

• Stamps.com Stainless Steel 5 lb. Digital Scale
• DYMO M25 25 lb Digital Postal Scale

Seeread_stupid.php orusbscale.c if you want to understand how it works at a glance.

composer require sanmai/usb-scale-reader

And then:

$reader = \USBScaleReader\Reader::fromDevice('/dev/scale');$weightInGrams =$reader->getWeight();var_dump($reader,$weightInGrams);

Sample output:

class USBScaleReader\Reader#2 (5) {  public $report =>  int(3)  public $status =>  int(4)  public $unit =>  int(2)  public $exponent =>  int(0)  public $weight =>  int(144)}int(144)

Add to/etc/udev/rules.d/80-persistent-scale.rules:

KERNEL=="hidraw*", ATTRS{manufacturer}=="Maker Name", SYMLINK+="scale"KERNEL=="hidraw*", SUBSYSTEM=="hidraw", MODE="0664", GROUP="plugdev"

Maker name is eitherStamps.com orDYMO.

And then reconnect your scale.

For other makers see:

udevadm info -a -p  $(udevadm info -q path -n /dev/hidrawN)

These rules imply that you should be inplugdev for the scripts to work.

There is alsoa simple reading program written in C.

To build it and run tests against PHP implementation:

cd examplemake test

Usage is as simple as it can be:

./usbscale /dev/hidraw3

Outputs something like

70.87 g