Encrypted bootloader.

[aberco]

I've found a pretty nice tutorial with instructions to set up the diolan bootloader, with extra infos added to diolan's official website (which are pretty straightforward already). There's apparently a bug in EEPROM bootloader triggering with a proposed fix for it.

So far I'm having a hard time running the code. I ported it to 18F4550 by modifying all the references to the 18F4455, and added the missing config bits for the extra code space. All the define for the config (and especially the oscillator) should be ok, as I made a little LED blink program in PBP using the same config and which does work.

The bootloader compiles in MPLAB, I programmed it and inserted by hand the HEX code of my blinking led program at address $0800. The bootloader does behave as expected, after reset, if the loader button is pressed, the LED never blinks which tells that the bootloader is engaged. However it does not shows on the USB peripherials (and I declared existing VID/PID in the config). Bootloader LED never light up too...

Time for more troubleshooting!

[HenrikOlsson]

Guys,
I'm following this with interest and please continue the discussion. However, I was and still am looking for an encrypted serial non USB bootloader so if anyone stumbles across one please let me know!

/Henrik.

[aberco]

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!).