Requesting SPI Example, Altera Nios II

Hi, I am currently trying on a project which need to send a data via SPI from DE0-Nano to DE2-115 board. For some how, I got the correct answer sometime but I also receiving others dummy data.

These are what I am thinking:

Is it the timing problem not match while transferring data from DE0 to DE2-115 receiving? Or I need to set up interrupts for both?

I am still confusing how to use while((STATUS(base)&RRDY)==0) << something like that. How it works? I have read the UserManual about SPI but I am still confusing. Any pro wanna to explain more briefly(friendly) about how to use these functions?:confused:

This is my current progress,

I am transferring 0xAA which is 170 in dec from the DE0 once I press button1(slave selection) from the DE2 board. Both boards, they are transferring and receiving but some time there are some errors at the receiving part which I will be receiving 0, 4, 42 randomly:(. Thus, I am wondering can anyone provide some SPI examples or advise for me?

Thank a lot.