Is there any tutorial to operate OTA_DFU and USB_DFU at the same time?

[ParanBada]

hello,
I developed a custom board using nRF52840, and secured_ota_dfu is working well.
But at the same time, I want to do DFU using USB.
Then, there are two bootloaders. What should I do?
Are there any related tutorials?

Best Regards

SunBae Yim.

[Hung Bui]

Hi SunBae, 

Have you tested with the USB DFU , did it work for you ? 
It's possible to combine BLE DFU and USB DFU. You just need to include the transport file for USB into the BLE bootloader. 
There are some tickets earlier discussed about this: 
1. Official BLE and UART Combined DFU bootloader? 

2.  USB DFU combined with Buttonless BLE DFU Please pay attention to the last reply.