Question about virtual com port

[Jyoti Bhayana]

I have a technical issue I am facing while doing development with Nordic NRF52840. I have an application which I am sending command though virtual com port using CDC ACM USB class. When the application is running the COM port shows as Port 30 on my windows. When I switch to my bootloader which also uses virtual com port using CDC ACM USB class, the port changes to 29 . Why the port is not remaining the same in both app and bootloader mode. Is there a way that the port number remains the same when I switch from my application to my bootloader application

In my sdk_config.h file I have same vendor and product ID. // Vendor ID ordered from USB IF: www.usb.org/.../ #ifndef APP_USBD_VID #define APP_USBD_VID 0x1915 #endif

// APP_USBD_PID - Product ID

// Selected Product ID #ifndef APP_USBD_PID #define APP_USBD_PID 0x520F #endif

[Sigurd]

I’m glad to hear that COM port issue have been solved. There is nothing that prevents you from writing your own bootloader with SDK 13. But since we have added a USB bootloader in SDK 14, you could save yourself a lot of time by upgrading and using that instead. You should at least take a look at it.

Regarding the USB driver/library, this is still labeled as experimental and considered a “work in progress”, until the production variant of the nRF52840 is released. Also note there is a lot of overall improvement of the USB driver in SDK 14.1. But since it’s still a “work in progress”, this means that the code base and APIs will change in-between SDK versions and will not necessarily be backwards compatible.