USBD with CDC ACM class Windows 10 maximum data rate

RE: USBD with CDC ACM class Windows 10 maximum data rate

prithvi25 — Sat, 25 Jan 2020 11:04:14 GMT

How did you test this speed?
I would like to know the software.
Because I am getting speeds up to 38 Kbps.

RE: USBD with CDC ACM class Windows 10 maximum data rate

ovrebekk — Thu, 27 Sep 2018 08:28:39 GMT

Hi Vasileios

This is a limitation by Windows, yes. On Linux we see higher data rates.

Best regards
Torbjørn

RE: USBD with CDC ACM class Windows 10 maximum data rate

Sebastian — Tue, 25 Sep 2018 15:06:31 GMT

Hello ovrebekk,

Thanks for the quick answer. I have run my own experiment and can confirm this number now.

Is there an explanation about this limit? Is it a matter of the Windows driver (usbser.sys) or a limitation imposed by the USB protocol operated as CDC?

I mean what happens if one keeps loading the 'app_usbd_cdc_acm_write' routine with more and more bytes by increasing the 'length' function parameter?

Thank you for your answers.

RE: USBD with CDC ACM class Windows 10 maximum data rate

ovrebekk — Tue, 25 Sep 2018 12:31:45 GMT

The team was quick to respond, and here are their results:

MSC write zeros to an empty drive (Linux): 513 kB/s (4104 kbit/s)

CDC ACM binary file transfer (Windows): 215 kB/s (1720 kbit/s)

Best regards
Torbjørn

RE: USBD with CDC ACM class Windows 10 maximum data rate

Sebastian — Tue, 25 Sep 2018 07:57:53 GMT

Thanks ovrebekk

RE: USBD with CDC ACM class Windows 10 maximum data rate

ovrebekk — Tue, 25 Sep 2018 07:54:47 GMT

Hi Vasileios

I have checked with the team, and they agreed to redo the tests for the latest SDK.

I don't know how quickly the results will be ready, but as soon as they are I will update this case with their findings.

Best regards
Torbjørn