Raspberry Pi Zero Smart Barcode Scanner

Requirements

• Raspberry Pi Zero 2W
• SD Card with Raspberry Pi OS Bookworm (with Legacy Camera System Disabled)
• Pi Camera v1/v2 and Cable
• Rotary Encoder with Button
• Push button for scan trigger
• ST7789 TFT LCD (Other SPI LCDs may work, but haven't been tested)
• (Optional) 30mm Fan - only required for overclocking
• USB Cable (Micro-B to USB-A or directly solder USB-A cable to pads)

3D Printed handheld Scanner

The 3D Printed Scanner is a modular and compact handheld scanner housing.

Required Parts

• Adafruit 1.54in ST7789 Display

Warning

The 3D models are made for the pre-July 24, 2019 displays. Slight modifications are required for the newer models.

<img src="https://cdn-shop.adafruit.com/970x728/3787-13.jpg" alt="Product photo" width=120></img>

• Raspberry Pi Zero 2W

  

• 16x Neopixel Ring

  

• KY-040 Rotary Encoder PCB

  

• 6x6x9 Tactile Push Button

• 5mm LED (Optional for Power Indication)

• PS1240P02BT (or similar) 3V 12.2mmx6.5mm Piezo Buzzer

• 5V 2A Power Supply (hard-wired into scanner, or modify the base for a connector of your choice)

• USB-A Cable with end cut off (for hard-wiring into scanner)

Hardware Setup

• Follow the Adafruit LCD wiring guide

  The default configuration uses the wiring available here

• Encoder Wiring

GPIO Pin	Encoder
GPIO17	Encoder A/CLK
GPIO18	Encoder B/DAT
GPIO27	Encoder Btn
GND	GND
3.3V	+

• Trigger Wiring

GPIO Pin	Button Pin
GND	Pin 1
GPIO20	Pin 2

• LED Wiring

GPIO Pin	LED Pin
GND	GND
5V	+
GPIO21	DAT_IN

• Buzzer Wiring

GPIO Pin	Buzzer Pin
GND	1
GPIO19	2

• Connect the Pi Camera

Installation

• Install System Packages

  sudo apt install python3-picamera2 python3-venv python3-pip libzbar-dev fonts-dejavu git supervisor

• Install USB Gadget Driver

Important

A reboot is required after this step

```console
git clone https://github.com/thewh1teagle/zero-hid
cd zero-hid/usb_gadget
sudo ./installer
sudo reboot
```

• Clone Repo

  git clone https://github.com/meowmeowahr/rpi-barcode-scanner && cd rpi-barcode-scanner

• Create Environment

  python3 -m venv .venv
  source ./.venv/bin/activate
  pip install uv
  uv sync

• Link pykms and libcamera

  ln -s /usr/lib/python3/dist-packages/pykms ./.venv/lib/python3.11/site-packages
  ln -s /usr/lib/python3/dist-packages/libcamera ./.venv/lib/python3.11/site-packages

• (Optional) Test Camera

  libcamera-hello

  You should see output containing something like the following

  [1:10:17.433392327] [2017]  INFO Camera camera_manager.cpp:326 libcamera v0.5.0+59-d83ff0a4
  [1:10:17.500249834] [2020]  WARN RPiSdn sdn.cpp:40 Using legacy SDN tuning - please consider moving SDN inside rpi.denoise
  [1:10:17.506046852] [2020]  INFO RPI vc4.cpp:447 Registered camera /base/soc/i2c0mux/i2c@1/ov5647@36 to Unicam device /dev/media3 and ISP device /dev/media0
  

• Create the configuration

  We will copy the example configuration file to the home directory, where it will be detected by the autostart script.

  cp config.yml ~/config.yml

  Get the UDC device address

  ls /sys/class/udc

  You should get something like the following

  3f980000.usb
  

  Note down this value, and set it in the configuration section, hid/udc

Note

If there are multiple device addresses, you will need to trial-and-error them. Try each, and restart the scanner. The connection status in the top left should reflect if the USB-HID interface is connected.

You can restart the scanner process with sudo supervisorctl restart scanner

• Configure Autostart

  sudo systemctl enable supervisor
  sudo systemctl start supervisors

  Edit the /etc/supervisor/conf.d/barcode-scanner.conf file to contain the following:

Note

Replace /home/scanner with your user path

```conf
[program:scanner]
user=root
directory=/home/scanner
command=/home/scanner/rpi-barcode-scanner/.venv/bin/python /home/scanner/rpi-barcode-scanner/main.py

autostart=true
autorestart=true
stdout_logfile=/var/log/barcode-scanner/stdout.log
stderr_logfile=/var/log/barcode-scanner/stderr.log
```

Start the scanner

```console
sudo mkdir /var/log/barcode-scanner
sudo supervisorctl start scanner
```

Configuration

tbd

FAQ

Q: The scanner application fails on auto-start.

A:

1. Check log files

   cat /var/log/barcode-scanner/stderr.log
   cat /var/log/barcode-scanner/stdout.log

2. Check service startup

   sudo supervisorctl status scanner
   sudo supervisorctl start scanner
   sudo supervisorctl status scanner

   You should get something like the following:

   scanner                          RUNNING   pid 2469, uptime 0:02:43
   

Licenses

This project is licensed under the MIT License.

The contents of the fasthid and vnc directories are licensed under the LGPLv3.