Voltage on output pin

[Altera_Forum]

I have a de2 altera with cyclone ii fpga. 

When i see the voltage on the oscilloscope of the output pin (expansion header), it is always 3.3 Volts also if i assign in the assignment editor 1.5V, 1.8V etc... Why?

[Altera_Forum]

The voltage you get at the output depends on the voltage that is applied to the specific IO bank of your FPGA. It depends on how your board has been designed. Besides of that you can change to specific IO standards. 

 But in your case, given a fixed DE2 board, I do not see how you can change the high level voltage.

[Altera_Forum]

You shold read about i/o standards (http://www.altera.com/literature/hb/cyc2/cyc2_cii5v1_04.pdf)

[Altera_Forum]

i've read about i/o standards but all the combination of input output voltage bring to 3.3 Volts on output pin of the expansion header

[Altera_Forum]

As sanmao explained, the DE2 board doesn't allow other I/O voltages than 3.3V. It's a hardware property (fixed by the respective VCCIO supply of each bank) and can't be modfied by FPGA configuration.