Accessories

Table of Contents

• Accessories

  • USB Ports

  • USB Devices

    • Polling Frequency

    • Gamepads

  • History

  • Bibliography

USB Ports

Universal Serial Bus (USB) is a common connector for accessories. Real world speeds for USB are about 30% less than the theoretical maximum speeds.

Name (New)	Name (Original)	Maximum Theoretical Speed (Gbps)	Real World Speed (Gbps)	Real World Speed (MBps)
USB 4		40	32	4000
USB 3.2 Gen 2x2	USB 3.2	20	16	2000
USB 3.2 Gen 2x1	USB 3.1 and USB 3.1 Gen 2	10	7.2	900
USB 3.2 Gen 1x2		10	7.2	900
USB 3.2 Gen 1	USB 3.0 and USB 3.1 Gen 1	5	3.2	400
USB 2.0		0.480
USB 1.1 Hi-Speed		0.012
USB 1.1 Low Speed		0.0015

[2]

As of USB 4, Thunderbolt 4 is natively supported with all cables and interfaces. All Thunderbolt 3 interfaces are USB type-C but not all USB type-C interfaces are Thunderbolt. All Thunderbolt 4 interfaces are USB 4 and vice-versa. [3]

USB Devices

Polling Frequency

The polling frequency of a USB device can be set based on the type of device it is:

• jspoll = Joystick (gamepad)

• kbpoll = Keyboard

• mousepoll = Mouse

An interval of time in miliseconds is configurable for the polling frequency. The default interval is 10ms. Linux uses this equation to calculate the frequency (Hz) that it should use for checking input from a device: <RATE> Hz = 1000 / <INTERVAL> ms. A lower interval will make a device more responsive but it will also use more processing power.

Here is how to change the pollling frequency:

• Temporary

  • Syntax:

    $ echo "<INTERVAL>" | sudo tee /sys/module/usbhid/parameters/<DEVICE>
    

  • Example (250 Hz USB mouse):

    $ echo "4" | sudo tee /sys/module/usbhid/parameters/mousepoll
    

• Permanent

  • Syntax:

    $ sudo vim /etc/default/grub
    GRUB_CMDLINE_LINUX_DEFAULT="usbhid.<DEVICE>=<INTERVAL>"
    $ sudo grub-mkconfig -o /boot/grub/grub.cfg
    

  • Example (500 Hz USB keyboard):

    $ sudo vim /etc/default/grub
    GRUB_CMDLINE_LINUX_DEFAULT="usbhid.kbpoll=2"
    $ sudo grub-mkconfig -o /boot/grub/grub.cfg
    

[4]

Gamepads

A gamepad is a game controller that usually has thumbsticks, triggers, and buttons.

Top gamepads [1]:

1. Xbox 360 Controller

2. PS4 Controller

3. Xbox One Controller

4. PS3 Controller

5. Steam Controller

History

• Latest

Bibliography

1. “Controller Gaming on PC.” Steam Blog. September 25, 2018. Accessed August 17, 2021. https://steamcommunity.com/games/593110/announcements/detail/1712946892833213377

2. “USB 3.2 Speed Comparison & Drive Benchmark.” Everything USB. November 2019. Accessed August 25, 2021. https://www.everythingusb.com/speed.html

3. “USB 3, USB 4, Thunderbolt, & USB-C — everything you need to know.” AppleInsider. August 24, 2020. Accessed August 25, 2021. https://appleinsider.com/articles/20/08/24/usb-3-usb-4-thunderbolt-usb-c—-everything-you-need-to-know

4. “Mouse polling rate.” Arch Wiki. January 25, 2022. Accessed February 11, 2022. https://wiki.archlinux.org/title/mouse_polling_rate