A question on traps

[mahdi259]

Hi
Sorry I have a question about traps. when does a load access fault occur?

[NikLeberg]

Hi there @mahdi259

The load access exception generally occures when either:

• the neorv32 internal bus aborts an access with err (as opposed to ack): This can happen if for example the IMEM is implemented read-only but the CPU tried to write to it. But it can also be generated if an nonexistant address (in the void) is accessed. Or also it the memory alignment was not valid (reading a single byte from an address that only supports 32-bit/word accesses).
• the external memory xbus aborts an access with err: IF you have attached something to the xbus, then it might generate an error if it is not accessed correctl.

For more information, see section 3.9. Traps, Exceptions and Interrupts in the datasheet.

If the problem persists, feel free to share your NEORV32 setup and we may point you to the some possible causes.

[mahdi259]

Sure, thanks a lot.

[mahdi259]

It seems that the problem was with memory sizes. It got load access fault trap when it returned from a function and while the sp of main function was reloaded. I increased each memory size to 1MB and it works without trap now!
Thanks a lot

[NikLeberg]

Glad to hear!