Controlling USB devices is a critical aspect of many Raspberry Pi projects, allowing users to manage peripherals such as keyboards, mice, storage devices, and more. This article will guide you through the process of controlling USB devices using a Raspberry Pi, including how to detect connected devices, manage power, and interact with USB peripherals programmatically. Understanding how to control USB devices can enhance your ability to create more sophisticated and responsive projects.

Examples:

1. Detecting Connected USB Devices: To list all connected USB devices, you can use the lsusb command. This command provides information about each USB device connected to your Raspberry Pi.

   lsusb

   Example Output:

   Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
   Bus 001 Device 002: ID 046d:c534 Logitech, Inc. Unifying Receiver

2. Managing USB Power: You can control the power to USB ports using the uhubctl utility. First, install uhubctl:

   sudo apt-get update
   sudo apt-get install uhubctl

   To turn off power to a specific USB port:

   sudo uhubctl -l 1-1 -p 2 -a off

   To turn the power back on:

   sudo uhubctl -l 1-1 -p 2 -a on

3. Interacting with USB Devices Programmatically: Python can be used to interact with USB devices. The pyusb library is a useful tool for this purpose. First, install pyusb:

   pip install pyusb

   Example Python script to list USB devices:

   import usb.core
   import usb.util
   
   # Find all devices
   devices = usb.core.find(find_all=True)
   
   # Loop through devices and print information
   for device in devices:
      print(f"ID: {device.idVendor}:{device.idProduct}")
      print(f"Manufacturer: {usb.util.get_string(device, device.iManufacturer)}")
      print(f"Product: {usb.util.get_string(device, device.iProduct)}")
      print("------")

4. Automating USB Device Detection: You can create a udev rule to automate actions when a USB device is connected. Create a new udev rule file:

   sudo nano /etc/udev/rules.d/99-usb.rules

   Add the following content to trigger a script when a USB device is connected:

   ACTION=="add", SUBSYSTEM=="usb", RUN+="/path/to/your/script.sh"

   Example script.sh:

   #!/bin/bash
   echo "USB device connected" >> /home/pi/usb_log.txt

   Make the script executable:

   chmod +x /path/to/your/script.sh

   Reload udev rules:

   sudo udevadm control --reload-rules