Hi Henrik! I would rather work with serial communication too! USB is clean and easy on the user side of things but it is far more challenging for us programmers. Maybe diolan's encryption routine can be reused within a serial bootloader, but that mean coding in ASM. The good side of things is that the code for encrypting the HEX code for the target is available, and communication protocol would still be handled by the original serial loader.
Well, it seems that I have no luck with USB on my little 18F4550 development board. Since I switched to 13/14K50 I have not managed to get anything running again on the 4550. I think that I managed to implement correctly the bootloader, but the USB interface is completely unresponsive. This is also true with a couple of other test programs (DT_HID260, HID demo, CDC demo). The configuration seems to be fine though, it run at the correct speed and USB module should be clocked at 48Mhz...
Maybe I'll concentrate my next efforts on porting the bootloader to 13/14K50, which is the MCU I really need for my projects (and I have USB working with it!).
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