Accessories¶
Table of Contents
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]
Bibliography¶
“Controller Gaming on PC.” Steam Blog. September 25, 2018. Accessed August 17, 2021. https://steamcommunity.com/games/593110/announcements/detail/1712946892833213377
“USB 3.2 Speed Comparison & Drive Benchmark.” Everything USB. November 2019. Accessed August 25, 2021. https://www.everythingusb.com/speed.html
“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
“Mouse polling rate.” Arch Wiki. January 25, 2022. Accessed February 11, 2022. https://wiki.archlinux.org/title/mouse_polling_rate