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Honored Contributor I

Stratix3 Dev Kit, Using HSMC ports as I/O

Hi, Guys, 


I've been experiencing I/O problems of the port for about a month but still have no clue of solving it. 


First, I got a DVI RX/TX d-card, manufactured by Terasic ( I hooked up the card and download the loopback demo made by Terasic. With SignalTapII, I found the pixel clock signal can be recognized by the FPGA chip but can not be used to trigger any internal register of the chip. 


Then, I powered on a VGA decoder/digitizer and connect the pixel clock to each of the 40 pins on a HSMC Debug Breakout Header d-card, which is an accessory card in the kit. The result is interesting: 

For some pins, I can observe the input clock waveform in SignalTapII and can use the clock to trigger internal registers of the device; 

For some other pins, the clock waveform is observable but can not bu use as triggering clock of device register; 

For the rest of the pins, clock waveform is not even observable, I got constant 0 or 1 in the SignalTapII. 


I'll attach my result along with schematic of both of the d-card I mentioned. 


So...does any one know the reason of this problem or any suggestion of work around? 


Any help is appreciated, thanks! 


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Honored Contributor I

I can't believe it. According to my knowledge, all Stratix 3 pins dedicated as differential I/O can be used single ended. 

- they can feed the FPGA logic 

- they can be acquired by SignalTap, if configured correctly 


Is the loopback test expected to work with the DVI card? 

Did you assign suitable I/O standards to then pins?