Kiwy-Signage/working_files/CARD_READER_FIX.md

Card Reader Fix - Multi-USB Device Support

Problem Description

When a USB touchscreen was connected to the Raspberry Pi, the card reader authentication was not working. The system reported "no authentication was received" even though the card reader was physically connected on a different USB port.

Root Cause

The original find_card_reader() function used overly broad matching criteria:

1. It would select the first device with "keyboard" in its name
2. USB touchscreens often register as HID keyboard devices (for touch input)
3. The touchscreen would be detected first, blocking the actual card reader
4. No exclusion logic existed to filter out touch devices

Solution

The fix implements a priority-based device selection with exclusion filters:

1. Device Exclusion List

Devices containing these keywords are now skipped:

• touch, touchscreen
• mouse, mice
• trackpad, touchpad
• pen, stylus
• video, button, lid

2. Three-Priority Device Search

Priority 1: Explicit Card Readers

• Devices with "card", "reader", "rfid", or "hid" in their name
• Must have keyboard capabilities (EV_KEY)
• Excludes any device matching exclusion keywords

Priority 2: USB Keyboards

• Devices with both "usb" AND "keyboard" in their name
• Card readers typically appear as "USB Keyboard" or similar
• Excludes touch devices and other non-card peripherals

Priority 3: Fallback to Any Keyboard

• Any keyboard device not in the exclusion list
• Used only if no card reader or USB keyboard is found

3. Enhanced Logging

The system now logs:

• All detected input devices at startup
• Which devices are being skipped and why
• Which device is ultimately selected as the card reader

Testing

Using the Test Script

Run the enhanced test script to identify your card reader:

cd /home/pi/Desktop/Kiwy-Signage/working_files
python3 test_card_reader.py

The script will:

1. List all input devices with helpful indicators:

   • ** LIKELY CARD READER ** - devices with "card" or "reader" in name
   • (Excluded: ...) - devices that will be skipped
   • (USB Keyboard - could be card reader) - potential card readers

2. Auto-detect the card reader using the same logic as the main app

3. Allow manual selection by device number if auto-detection is wrong

Example Output

=== Available Input Devices ===

[0] /dev/input/event0
    Name: USB Touchscreen Controller
    Phys: usb-0000:01:00.0-1.1/input0
    Type: Keyboard/HID Input Device
    (Excluded: appears to be touch/mouse/other non-card device)

[1] /dev/input/event1
    Name: HID 08ff:0009
    Phys: usb-0000:01:00.0-1.2/input0
    Type: Keyboard/HID Input Device
    ** LIKELY CARD READER **

[2] /dev/input/event2
    Name: Logitech USB Keyboard
    Phys: usb-0000:01:00.0-1.3/input0
    Type: Keyboard/HID Input Device
    (USB Keyboard - could be card reader)

Verifying the Fix

1. Check Logs: When the main app starts, check the logs for device detection:

   tail -f /path/to/logfile
   

   Look for messages like:

   CardReader: Scanning input devices...
   CardReader: Skipping excluded device: USB Touchscreen Controller
   CardReader: Found card reader: HID 08ff:0009 at /dev/input/event1
   

2. Test Card Swipe:

   • Start the signage player
   • Click the edit button (pencil icon)
   • Swipe a card
   • Should successfully authenticate

3. Multiple USB Devices: Test with various USB configurations:

   • Touchscreen + card reader
   • Mouse + keyboard + card reader
   • Multiple USB hubs

Configuration

If Auto-Detection Fails

If the automatic detection still selects the wrong device, you can:

1. Check device names: Run test_card_reader.py to see all devices
2. Identify your card reader: Note the exact name of your card reader
3. Add custom exclusions: If needed, add more keywords to the exclusion list
4. Manual override: Modify the priority logic to match your specific hardware

Permissions

Ensure the user running the app has permission to access input devices:

# Add user to input group
sudo usermod -a -G input $USER

# Logout and login again for changes to take effect

Files Modified

1. src/main.py

   • Updated CardReader.find_card_reader() method
   • Added exclusion keyword list
   • Implemented priority-based search
   • Enhanced logging

2. working_files/test_card_reader.py

   • Updated list_input_devices() to show device classifications
   • Updated test_card_reader() to use same logic as main app
   • Added visual indicators for device types

Compatibility

This fix is backward compatible:

• Works with single-device setups (no touchscreen)
• Works with multiple USB devices
• Fallback behavior unchanged for systems without card readers
• No changes to card data format or server communication

Future Enhancements

Potential improvements for specific use cases:

1. Configuration file: Allow specifying device path or name pattern
2. Device caching: Remember the working device path to avoid re-scanning
3. Hot-plug support: Detect when card reader is plugged in after app starts
4. Multi-reader support: Support for multiple card readers simultaneously