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Altera_Forum
Honored Contributor I
1,793 Views

Inout pin Warning

Hi, 

 

I am using Quartus version 17.1. I am receiving this warning message: 

 

Warning (12620): Input port OE of I/O output buffer "fx3_dq[1]~output" is not connected, but the atom is driving a bi-directional pin 

 

from Quartus while compiling. fx3_dq is 8 bits wide and is an inout wire connected from another module to the top level.  

Why am I receiving this message?  

 

I found this page : https://www.altera.com/support/support-resources/knowledge-base/solutions/rd01262015_264.html 

but it says this only occurs in version 14.1 and earlier. I also created tried changing the output by assigning it to high if an output enable signal is high and low if low, but I still receive this message. 

 

-Thank you
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6 Replies
Altera_Forum
Honored Contributor I
34 Views

Hi, 

 

Just implemented logic you have described in both pro & std but not able to get the warning mentioned. 

1. Just delete the incremental_db & db folder and try. 

 

  • Which edition of Quartus (pro/std) are you using? 

  • Attach the code & message log from Quartus. 

 

 

Best Regards, 

Anand Raj Shankar 

(This message was posted on behalf of Intel Corporation)
Altera_Forum
Honored Contributor I
34 Views

The output should be tri-stated (z) if oe is low, not low. Can you post your code?

Altera_Forum
Honored Contributor I
34 Views

I am using Quartus Prime Standard Edition  

 

fx3_dq is directly connected to FPGA pins, but is also passed into a module like so: 

 

fx3 fx3_inst( 

.reset(reset) 

,.clk(clk) 

,.fdata(fx3_dq) 

,.sloe(fx3_sloe_n) 

..... 

 

); 

 

This is just an example and inside the module there is an assign like so for fdata: 

 

assign fdata = (slwr_loopback_1d_) ? 8'dz : data_from_hps; 

 

The code is the sample project from FX3; I'm not sure if I can post it but I have a link to the page. 

 

http://www.cypress.com/documentation/application-notes/an65974-designing-ez-usb-fx3-slave-fifo-inter... 

 

On my top level do I also need a tri-state as mentioned? Or should the tri-state be taken care of with the assign statement in the module? 

 

Thank you
Altera_Forum
Honored Contributor I
34 Views

You can't have internal tri-states. They can only be at the top level. Is slwr_loopback_1d_ your oe signal?

Altera_Forum
Honored Contributor I
34 Views

 

--- Quote Start ---  

You can't have internal tri-states. They can only be at the top level. Is slwr_loopback_1d_ your oe signal? 

--- Quote End ---  

 

 

Okay, I will move the assign to my top level instead. Is it because tri-states only apply directly to the FPGA pins?
Altera_Forum
Honored Contributor I
34 Views

Yes. Tri-state logic is only in the I/O.

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