how to merge cdc funcation in ncs sdk project desktop?

[pipixia_1_1]

Hi,nordic team，

im use nrf52840 develop my product with sdk ncs 2.6.the speed of desktop dfu is so slow,and the speed of configurator channel is also slow.i want to transfer my data by cdc .if there is some eexample to show how should i to do?or som document? 

[Lorenzo Amicucci]

if timing is critical during the file transfer, one other option is to use SMP protocol and MCUmgr. 
As mentioned in the documentation, the same mouse can support both type of transports ( we do this already now): the same mouse can be updated using config channel when connected to the PC over BLE, but it can updated using the SMP protocol when connected over BLE to the smartphone - nRF Connect for Mobile app. The important thing is that you include MCUboot as bootloader. 

So, you could try to use SMP over BLE also when mouse is connected to the PC. SMP is faster typically. 
However, you need to keep into consideration this:

- here you find the PC libraries that implement the SMP Client 
https://docs.zephyrproject.org/latest/services/device_mgmt/mcumgr.html#tools-libraries
(for mobile phone you can get the libraries from our mobile apps nRF Connect for Mobile and nRF Connect Device Manager - both android and ios)

- in linux, you have more choices, as mcumgr-client works also over BLE.

- in windows, the mcumgr-client will not work over bluetooth, only over USB. So you will need to use either AuTerm or mcumgr-web. Note: these are supported by the community, not released by Nordic, so they may have some bugs not under our control.
Important: such 3rd party PC clients are not able to use Direct-XIP mode. So you will need to disable that feature. That means they only support swap of the images between slots after the reset. This change of slot will also take some time. So, even if you reduce the time in transferring the image, after resetting time, it may take a bit time to swap the images between slot 1 and 0. Overall, it should be less than 3 minutes, and maybe it is ok for you (because you have a prompt that inform customers when to reset the device). 

If you can use USB for file transfer, than there may be other options. Please let us know if you can use USB.