Wireless Barcode Scanner

Basic tutorial of how to setup the NADAMOO Wireless Barcode Scanner with the Raspberry Pi.

PARTS:

CanaKit Raspberry Pi 4 4GB Starter Kit – https://amzn.to/2Jrlbfj

NADAMOO Wireless Barcode Scanner – https://amzn.to/373BckB

SETUP:

1. Install EVDEV 1.2.0 library

sudo pip3 install evdev==1.2.0

2. Check barcode device name and path exists

sudo python3 /usr/local/lib/python3.7/dist-packages/evdev/evtest.py

You should see “MMicroelectronics MM32 Joystick” if device is detected

3. Run Script

sudo python3 barcode_wireless.py

CODE:

evdev documentaion: https://python-evdev.readthedocs.io/en/latest/index.html

#!/usr/bin/env python3
from evdev import InputDevice, ecodes, list_devices, categorize
import signal, sys

barCodeDeviceString = "MMicroelectronics  MM32 Joystick" # barcode device name

scancodes = {
    # Scancode: ASCIICode
    0: None, 1: u'ESC', 2: u'1', 3: u'2', 4: u'3', 5: u'4', 6: u'5', 7: u'6', 8: u'7', 9: u'8',
    10: u'9', 11: u'0', 12: u'-', 13: u'=', 14: u'BKSP', 15: u'TAB', 16: u'Q', 17: u'W', 18: u'E', 19: u'R',
    20: u'T', 21: u'Y', 22: u'U', 23: u'I', 24: u'O', 25: u'P', 26: u'[', 27: u']', 28: u'CRLF', 29: u'LCTRL',
    30: u'A', 31: u'S', 32: u'D', 33: u'F', 34: u'G', 35: u'H', 36: u'J', 37: u'K', 38: u'L', 39: u';',
    40: u'"', 41: u'`', 42: u'LSHFT', 43: u'\\', 44: u'Z', 45: u'X', 46: u'C', 47: u'V', 48: u'B', 49: u'N',
    50: u'M', 51: u',', 52: u'.', 53: u'/', 54: u'RSHFT', 56: u'LALT', 100: u'RALT'
}


def signal_handler(signal, frame):
    print('Stopping')
    dev.ungrab()
    sys.exit(0)


if __name__ == '__main__':
    # find usb hid device
    devices = map(InputDevice, list_devices())
    for device in devices:
        # print(device.name, device.fn)
        if barCodeDeviceString in device.name:
            dev = InputDevice(device.fn)
        else:
            print('No barcode device found')
            sys.exit()

    signal.signal(signal.SIGINT, signal_handler)
    dev.grab()

    # process usb hid events and format barcode data
    barcode = ""
    try:
        for event in dev.read_loop():
            if event.type == ecodes.EV_KEY:
                data = categorize(event)
                if data.keystate == 1 and data.scancode != 42: # Catch only keydown, and not Enter
                    key_lookup = scancodes.get(data.scancode) or u'UNKNOWN:{}'.format(data.scancode) # lookup corresponding ascii value
                    if data.scancode == 28: # if enter detected print barcode value and then clear it
                        print(barcode)
                        barcode = ""
                    else:
                        barcode += key_lookup # append character to barcode string
    except KeyboardInterrupt:
        dev.close()

References: https://stackoverflow.com/questions/21648595/python-evdev-and-bar-code-scanner