Errors, When Nios access pci complier's controle register.

:confused::confused::confused:

Hi, all

We build a SOPC system with nios2 cpu and pci compiler, and we want to send data to PC using PCI bus. We develop it under Quartus 9.0 and NIOS 9.0, the device is Cyclone II EP2C8Q208C8.

The pci compiler is set to mt32, nios cpu has different reset and clock signal between pci compiler. nios's data master and pci's BAR0 Non-prefetchable connect to the pci complier's controle register.

As we test the SOPC system first, we use nios to access pci complier's controle register: Read-Only Configuration Registers(0x2c00). Under debug mode, when running at the read process, the IDE said error and we find that when we access any controle register, it goes error.

the software is:

volatile alt_u32 *PCI_RO_Config = (alt_u32 *)(PCI_COMPILER_CONTROL_REGISTER_ACCESS_BASE + 0x2C00);

i = *PCI_RO_Config;

can someone has any suggestions? Thank u