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enable differential mode on alt_iobuf??

Altera_Forum
Honored Contributor II
1,045 Views

I have a project based on and Arria 10 SoC development board which using FMC ports (LVDS IO Standard). I have a bidrectional pin which is the "io" port in an alt_iobuf instance.  

The project synthesizes fully, but fails on the fitting, giving the error " can't on open-drain option for differential io pin". 

I have looked up the solution and everywhere says to enable differential mode on the IO buffer, but nowhere says how to enable it?. Here is the current instance: 

 

alt_iobuf IOBUFF_scl ( 

.i(1'b0), 

.oe(scl_oen), 

.io(scl), //bidirectional pin 

.o(scl_c_normal) 

 

); 

 

 

How do you enable differential mode? 

 

Dáire
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1 Reply
Altera_Forum
Honored Contributor II
127 Views

Not sure what you want to achieve. If it's bidirectional respectively multi-drop LVDS, review application note for BLVDS (bus LVDS).

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