USB CDC ACM max transfer speed

[Hiihtaja]

Hello !

I'm using  USB CDC ACM serial port in interrupt driven mode.

I can see driver operate by 64 bytes chunks.

Linux PC is used as data source and I can see 450KB/s in case of RX and about 250KB/S in case of TX.

Does those digits are good enough for nRF52840 ?

Can it be faster and generate less interrupts e.g not every 64 bytes ?

Or this is some fundamental constant #define NRFX_USBD_EPSIZE 64 e.g max packet size  for full speed USB and basically everything already fast enough ?

Regards,

Eugene

[Sigurd]

Hi,

Those numbers seem to be in line with what we have found. In our testing we have found the CDC example to yield approximately 215kB/s transfer speed on Windows, and over 300kB/s on Linux. 

Or this is some fundamental constant #define NRFX_USBD_EPSIZE 64 e.g max packet size  for full speed USB and basically everything already fast enough ?

Correct, 64 is the max for USB Full speed device.

[Hiihtaja]

Thank you !

Eugene