USB CDC and USART recommended practice

[whitehorsesoft]

When using USB CDC to communicate via USART, and interacting with USART data, in code is it recommended to interact with it at the USB side, or to interact with it at the USART side?

From what I can tell, both offer both polling and interrupt methods. The USART offers DMA access, but apart from that it's not clear what, if any, tradeoffs there are between USB CDC and USART.

[FBL]

Hi @whitehorsesoft 

For applications requiring higher data rates and USB connectivity, USB CDC is more convenient because USB CDC provides dedicated functions for managing data transfer efficiently: CDC_Receive CDC_Transmit to handle received/transmitted packets from the USB host using interrupt callbacks.

[TDK]

If the signal has to travel over UART, I would use UART. It is a much simpler interface with less things to go wrong. If the signal can be passed entirely over USB, and you need the speed, use usb.

Benefits to each:

• UART: simplicity
• USB: speed