Forum Discussion
Occasional ContributorCyclone III slave (PS) embedded memory errors
I think I've found the problem.
There is a trace connected to pin 76 on the master and pin 99 on the slave. Trace is pulled up to 3.3V via 2.2k
This **bleep** resistor was dead, and the trace was actually floating.
I didn't use this pins before, so I can't reveal the resistor is dead.
As I start to use it, all logic became a total mess. Something worked, something not. By elimination I found the culprit.
I can't explain how this trace connected with loading errors (when FPGA not even in user mode), but the fact is - replacing resistor solved all problems, ROMs working now (though I don't use them anymore).
Thanks to all, problem solved!
Occasional ContributorWhat worries me most - is it possible to these bit errors happens when the whole slave is being programmed? I mean, can this broke some functionality? AND gates becomes OR for example. All board always loaded correctly for now, but that's not so much code in the slave atm, it's ROM read, address decoding, couple of registers, some bus functionality.
I can do some workaround, for example, move ROMs to the external RAM, and load them from EPCS through ASMI megafunction. But this has no sense if there is a chance slave itself will not load correctly...
Is there some error checks inside Cyclones when they downloads firmware from EPCS? If so, why it not includes content of pre-initialized memory?
