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[SignalTap] why signals are synthesized out when SignalTap enabled?

Honored Contributor I

Hi All,  


I've met the strange phenomena - when I use the SignalTap-II instance (enable the SignalTap in Project Settings), it throws out some ports/nets in my design! It throws out exactly the nets/ports, which should be used in SignalTap (signals that are connected to FIFO IP)!  


I did a test case - ran the same Project, but with the disabled SignalTap and Quartus did not throw these signals out! 


What happens? Can anybody help?  


Thank you!
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1 Reply
Honored Contributor I



Are you referring to jtag ports/net created after adding stp file to design? 


Signal-Tap uses memory and LEs to establish scan like structure to tap the net/signal required from design and pass it down to the jtag protocol, Which is used for establishing the communication between the fpga and quartus signal tap GUI. 

because of this you may see the jtag ports. 


disabled signal-tap and remove the stp file from file directory and check.  


Best Regards, 

Anand Raj Shankar 

(This message was posted on behalf of Intel Corporation)