nrf5340: FW upgrade via USB CDC

[Jason]

Hi:

The MCUboot supports USB CDC and UART  recovery, and we also can upgrade the FW via BLE and UART normally at the application level.

I would like to know if the normal FW upgrade supports USB CDC as well. if yes, do you have any demo code? and what is the maximum speed of the USB CDC?

Thanks!

[Einar Thorsrud]

Hi,

You are free to use USB CDC also with "normal" updates. You can see an example of that in the SMP Server Sample (using the provided overlay files for USB CDC).

[Jason]

Hi, 

Thanks for your quick reply. 

One more question.

What is the maximum baud rate of the USB CDC and how to set the baud rate?

[Einar Thorsrud]

Hi,

The default baud rate is 115200. This is hard coded as CDC_ACM_DEFAULT_BAUDRATE in the implementation in cdc_acm.c. It can be configured from SW by setting CONFIG_UART_LINE_CTRL=y in the project configuration. You can see an example of that by looking at the set_uart_baudrate() function in uart_handler.c (this code is using UART and not CDC ACM, but the API is the same). In most cases you will not set the baud rate via CDC though, and you can detect it if the host does. PS: you can also poll the CDC state including baud rate as shown by poll_dtr() in usb_cdc_handler.c.

Einar