sanmai/usb-scale-reader

Standard USB scale reader library

USBScaleReader

, _(*1)

This library lets you read weight from a standard USB scale using pure PHP., _(*2)

Could be ported to other languages with ease, should they have unpack(), _(*3)

Tested with: - Stamps.com Stainless Steel 5 lb. Digital Scale - DYMO M25 25 lb Digital Postal Scale, _(*4)

See read_stupid.php or usbscale.c if you want to understand how it works at a glance., _(*5)

Usage

composer require sanmai/usb-scale-reader

And then:, _(*6)

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

Sample output:, _(*7)

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)

udev rules

Add to /etc/udev/rules.d/80-persistent-scale.rules:, _(*8)

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

Maker name is either Stamps.com or DYMO., _(*9)

And then reconnect your scale., _(*10)

For other makers see:, _(*11)

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

These rules imply that you should be in plugdev for the scripts to work., _(*12)

C version

There is also a simple reading program written in C., _(*13)

To build it and run tests against PHP implementation:, _(*14)

cd example
make test

Usage is as simple as it can be:, _(*15)

./usbscale /dev/hidraw3

Outputs something like, _(*16)

70.87 g