Did you found the way to solve this? I'm trying to also implement RunTime DFU via USB port. Did you suceeeded? Which is the best example to follow?
Check our pre-defined examples in USB library DFU in IAP mode. Else I missed your question ? Did you mean to have a composite example with a HID for example and DFU interfaces both active in run-time and once invoked for a device programming the DFUdriver will take the global control ?.
Retrieving data ...