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Altera_Forum
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15 years ago

Nios-II Address Bus XXXXXXXX normal?

About 5 cycles after reset has gone inactive, the Nios-II CPU drives 'X's (yes they are true X's, which typically means two signals are driving each other) onto the address and byte enable buses. Thi...
Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
15 years ago

Make sure you are resetting to a memory with valid instructions in it. Otherwise you'll probably have unknown data enter the instruction master then who knows what the masters will do after that.

If you are seeing an unknown address at the beginning of the simulation driven out but read and write are both idle then I wouldn't worry about that. If read or write are high and an unknown address is being sent then I would trace back in time to find out why.