【Infomedia】About nRF52840 USB communication function .

[FrankBi]

Dears,

1.I want to know when working at USB CDC mode, what's the phy rate could be supported? And what's real rate is it？

2.Could customer customized their private protocol using USB interface, except CDC and mass storage?

Thanks.

[ovrebekk]

Hi Frank

1.I want to know when working at USB CDC mode, what's the phy rate could be supported? And what's real rate is it？

The PHY rate is 12Mbps "full speed". 

The actual throughput when using CDC depends on the host operating system used. We ran some tests on this and measured up to ~215kB/s datarate on Windows 10, and up to 323kB/s on Linux. 

2.Could customer customized their private protocol using USB interface, except CDC and mass storage?

You are not limited to CDC or mass storage, and it is possible to implement other USB classes, but it's obviously a lot more work on the development side if you don't use one of the existing classes. 

Best regards
Torbjørn 

[FrankBi]

Thanks Torbjorn  for kindly reply. That means USB CDC mode could be tested to 215kB/s or 323kB/s,depend on different remote OS,right? Is there any space to improve it? Thank you so much.

[ovrebekk]

Hi Frank

Correct. We did some testing try to send as much data as possible from the host to the device, and we noticed that the host OS made an impact on the speed. 

This implies there is some overhead on the host side that can differ based on the USB drivers provided in Windows and Linux. 

There is no easy way to improve these numbers unfortunately, without affecting the reliability of the transfer. 

Best regards
Torbjørn