While working on a bootloader for uPSD3212, I came across a memory mapping problem, which I could not find to be documented, and I would like to have i confirmed by somebody else (and perhaps also on other types of uPSD3xxx, I have only the uPSD3212C).

The problem is: if I map the RAM+IOP into the same address space as any of the flash, then while only PSEN access is enabled for that flash in VM register, the PSEN reads (code fetches and MOVC reads) are read from the flash OK, but if both PSEN and RD access is enabled for that flash, any PSEN read from that area returns garbage (more precisely, it returns the low byte of address as if no memory is active at that time).

My particular setting was:

RAM        0000-07FF
IOP        0800-08FF
FS0        0000-3FFF
FS1        4000-7FFF
FS2        8000-BFFF
FS3        C000-FFFF
CSBOOT0    8000-9FFF
CSBOOT1    A000-BFFF

The fatal consequence is, that if in PSDSoftExpress under a similar memory mapping one sets the for primary flash powerup access both code and memory, it won't run the code in flash...

Can please anybody try and confirm (or not) these findings, or perhaps point me out some piece of documentation detailing this behaviour?

Jan Waclawek