FPGA DO negative offset

[SeanAhn]

Hello,

I'm Sean.

I'm using USB-7856R to test comparator VI generaing digital output.

Though I set FPGA's DO to have 3.3V output, it gives negative offset, the green signal lines shown in the picture below.

Finally, the positive peak is just around 1 V, not enough to connect other switching devices.

What should I do to have DO between 0 and +3.3 V?

Thanks in advance,

Sean Ahn

[crossrulz]

Did you connect the Digital Ground to your system ground?