Which USB class should I use for maximum data rates on nrf52840? And what is the maximum size of transfer if I use CDC_ACM?

[Akshay]

I want to transfer sensor data to a raspberry pi using the in-built USB on nrf52840. The example codes have the following classes: CDC_ACM, Audio, HID and Mass storage. I want to transfer data around 200 KB/s. Which class would be sufficient for the data rates? Also for the host side, will using USB serial port (ttyACM0) be fast enough for CDC_ACM or should I use libusb?

[Radoslaw Koppel]

According to our tests Windows CDC driver limits throughput to something around 2 Mbps. So it might be just fine for you. The fastest one seems to be MSC, but it would require quite a lot of tricks to use it to download logs. If CDC would not be fast enough I would go with libusb and accessing endpoints directly - it seems to be much easier than using MSC.

[Akshay]

Thank you, I'll see if I can get the required data rates using CDC. Is there an example code for NRF52840 if I use libusb to access endpoints directly?

[bjorn-spockeli]

I think you should be able to use the USBD example in examples\peripheral\usbd\pca10056 as a template, which uses the USB Device raw IP driver, see this Infocenter page for the documentation.

[Akshay]

Thank you Bjorn Spockeli. Got the USBD template code working for my application with libusb

[alexlöddeköpinge]

Hi, maybe this answer is too old but I try. What do you mean when you say "go with libusb and accessing endpoint directly"?