We have managed to get two systems in a state where the 'security fuse' is apparently blown.
We are trying to modify the standard BSL to use the UART instead of USB; fairly minimal change to the original.
When trying to program in the new BSL code via the IAR debugger memory verification failure is reported and then the processor is no longer accessible via JTAG.
The Elpotronic software reports that the security fuse is blown.
Assuming that the firmware we are trying to program in is valid what are the do's and don'ts of programming it in so we don't create any more bricked units?
Thanks in advance for any help.