How do I use PIO which is configured as InOut?

[Fjato]

Hi,

For a Cyclone V project I configured a PIO as InOut with a width of 1 bit in Qsys. Unfortunately I am not quite sure how to use the PIO to write and read data. So, which value do I need to write to which register to read from this PIO and which value do I need to write to which register to write from this PIO?

Thank you in advance.

[YuanLi_S_Intel]

Hi Fabian,

Apologize that i dont know which PIO you are referring to? Are you referring to IP or what?

Thank You.

[Fjato]

Hi Bruce,

sorry for the missing information. I am referring to the PIO Core with Avalon interace documented in https://www.intel.com/content/dam/www/programmable/us/en/pdfs/literature/hb/nios2/n2cpu_nii51007.pdf.

Thank you in advance.

[sstrell]

As the guide you pointed to states, you have to set direction in the direction register and then read or write the data register depending on the direction.

#iwork4intel

[Fjato]

Hi, thanks for your reply. But I am not speaking about the bidirectional setting.

The IOs can be configured as Input, Output, Bidirectional and InOut. The first three ones are self-explanatory for me and are well documented. What I would like to know is the fourth setting InOut. If setting a single IO to InOut, I have access to two IO pins in Quartus, one being fixed input and the other one being fixed output. So I doubt, that I can set the direction for the pin. Instead I would expect, that I can write data for the output pin to the data register and read data from the input pin from another data register. But I can not find out what's the correct address / offset for both data register (offset "0" and bit "1" would be the case for all the other settings Input, Output and Bidirectional).

I hope could point out a problem a bit more. Pleas let me know if I misunderstood something. Thank you in advance and best regards.

[Fjato]

Anyone, who can help? Thanks in advance and best regards.

[YuanLi_S_Intel]

OK, i understand what is your question already. For InOut, you have both input and output connected to the IP. Thus, you can just read / write the register 0 without the need to set register 1. Read Register 0 if you want to get the input and write register 0 if you want to write. Register 1 is only meant for bidirectional use only.