Why is the USB communication to my PCD lost after a program download?

FAQ #101518

 

Symptom
In case the user program accesses I/Os with addresses over 1024 on a PCD running firmware 1.14.23, the USB communication is lost just after download of the program (the PCD will remain in Halt state in this case)

Reason
The firmware does not correctly react to the access of the I/Os over 1024 (wich do not exist) and therefore gets a bus error on address 100D9FF2H.

Solution
Please avoid the access to I/Os with address 1024 (which makes no sense, these I/O do not exist).
Starting with firmware version 1.14.30, the PCD will no longer go in halt but just ignore these accesses.