Talk:Polling rate

I started a document some time back to remind myself of all the polling rates of the various USB interfaces (and PS/2). Still needs a bit of work on the math (and some validation to make sure it's correct before I think it's wiki quality). Perhaps some proper spec references for the USB polling rates as well. -HaaTa

PS/2

Interrupt based, usually. This is optional, and the OS can decide to poll the results from the PS/2 interface. The polling rate is likely around 125 Hz, but this is entirely dependent upon OS settings. Going from the PS/2 mouse protocol, this could be as bad as 10 Hz (possibly even worse).

Each 11 bit packet is around 900 us with a delay of at least 50 us between multiple packets (? not completely sure about this, depends on the keyboard implementation). This generally means about 1 ms per key, or 7 ms when pressing Ctrl + Alt + A + B + C + D + E.

Effective polling rate

Best case 1 key: 1000 Hz Best case 6 keys: 167 Hz Bad case 1 key: 10 Hz (due to OS polling)

References

• http://www.computer-engineering.org/ps2keyboard/
• http://www.computer-engineering.org/ps2protocol/
• http://wiki.osdev.org/%228042%22_PS/2_Controller
• http://wiki.osdev.org/PS/2
• http://wiki.osdev.org/PS/2_Keyboard
• http://wiki.osdev.org/Mouse_Input

USB 1.1/2.0 - Low Speed

Polling Rate: 125 Hz

Max Data Rate: 1.5 mbps

TODO - Data transmission analysis

USB 2.0 - Full Speed

Polling Rate: 1000 Hz

Max Data Rate: 12 mbps

USB 2.0 - Hi-Speed

Polling Rate: 8000 Hz

Max Data Rate: 480 mbps

TODO - Data transmission analysis

USB 3.0 - SuperSpeed (USB 3.1 Gen 1)

Polling Rate: 8000 Hz

Max Data Rate: 5 gbps

TODO - Data transmission analysis

USB 3.1 - SuperSpeed+ (USB 3.1 Gen 2)

Polling Rate: 8000 Hz

Max Data Rate: 10 gbps

TODO - Data transmission analysis