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@ronivaldo
Forked from jacksenechal/readscale.py
Created September 26, 2017 23:59
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Python script to read a USB scale in the Linux
#!/usr/bin/python
import os, time
import usb.core
import usb.util
import pygtk
pygtk.require('2.0')
import gtk
from sys import exit
import math
# DYMO M25
VENDOR_ID = 0x0922
PRODUCT_ID = 0x8004
# USPS 75lb scale (doesn't work yet...)
#VENDOR_ID = 0x04d9
#PRODUCT_ID = 0x8010
# find the USB device
dev = usb.core.find(idVendor=VENDOR_ID,
idProduct=PRODUCT_ID)
def main():
try:
# was it found?
if dev is None:
print "device not found"
exit()
else:
devmanufacturer = usb.util.get_string(dev, 256, 1)
devname = usb.util.get_string(dev, 256, 2)
print "device found: " + devmanufacturer + " " + devname
interface = 0
if dev.is_kernel_driver_active(interface) is True:
print "but we need to detach kernel driver"
dev.detach_kernel_driver(interface)
# use the first/default configuration
dev.set_configuration()
print "claiming device"
usb.util.claim_interface(dev, interface)
# XXX would be good to release it when we're done:
#
# print "release claimed interface"
# usb.util.release_interface(dev, interface)
# print "now attaching the kernel driver again"
# dev.attach_kernel_driver(interface)
# print "all done"
listen()
except KeyboardInterrupt as e:
print "\nquitting"
exit();
def grab():
try:
# first endpoint
endpoint = dev[0][(0,0)][0]
# read a data packet
attempts = 10
data = None
while data is None and attempts > 0:
try:
data = dev.read(endpoint.bEndpointAddress,
endpoint.wMaxPacketSize)
except usb.core.USBError as e:
data = None
if e.args == ('Operation timed out',):
attempts -= 1
print "timed out... trying again"
continue
return data
except usb.core.USBError as e:
print "USBError: " + str(e.args)
except IndexError as e:
print "IndexError: " + str(e.args)
def listen():
DATA_MODE_GRAMS = 2
DATA_MODE_OUNCES = 11
last_raw_weight = 0
last_raw_weight_stable = 4
print "listening for weight..."
while True:
time.sleep(.5)
weight = 0
print_weight = ""
data = grab()
if data != None:
raw_weight = data[4] + data[5] * 256
# +/- 2g
if raw_weight > 0 and abs(raw_weight-last_raw_weight) > 0 and raw_weight != last_raw_weight:
last_raw_weight_stable = 4
last_raw_weight = raw_weight
if raw_weight > 0 and last_raw_weight_stable >= 0:
last_raw_weight_stable -= 1
if raw_weight > 0 and last_raw_weight_stable == 0:
if data[2] == DATA_MODE_OUNCES:
ounces = raw_weight * 0.1
weight = math.ceil(ounces)
print_weight = "%s oz" % ounces
elif data[2] == DATA_MODE_GRAMS:
grams = raw_weight
weight = math.ceil(grams)
print_weight = "%s g" % grams
print "stable weight: " + print_weight
clipboard = gtk.clipboard_get()
clipboard.set_text(str(weight))
clipboard.store()
def probe():
for cfg in dev:
print "cfg: " + str(cfg.bConfigurationValue)
print "descriptor: " + str(usb.util.find_descriptor(cfg, find_all=True, bInterfaceNumber=1))
for intf in cfg:
print "interfacenumber, alternatesetting: " + str(intf.bInterfaceNumber) + ',' + str(intf.bAlternateSetting)
for ep in intf:
print "endpointaddress: " + str(ep.bEndpointAddress)
#probe()
main()
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