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Altera_Forum's avatar
Altera_Forum
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18 years ago

Cyclone III/HSMC pin voltage

I have a Cyclone III starter kit with the Bitec HSMC breakout adapter, and I need to interface with some 3.3V devices through the adapter pins.

It seems that even changing the pin voltage in the Quartus II pin assignments editor has no effect on the voltage I measure on the adapter output - I still measure 2.5V after configuring the proper pins to 3.3V.

Is this a limitation of the breakout adapter or am I missing some step to create 3.3V output? I have just set the "I/O standard" column for my desired bank/pins to 3.3 LVCMOS in the Pin Planner.

I have limited experience with Altera products and come from a purely software background, so forgive me if the answer is obvious.

1 Reply

  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    18 years ago

    Hello,

    I don't know about the details of the said hardware, but I/O voltage is primarly a hardware feature, defined by supplying the respective VCCIO with either 2.5 or 3.3 V. IO-standard should be set according to VCCIO but can't change the pin voltage.

    Regards,

    Frank