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Altera_Forum
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11 years ago

Help setting Cyclone III pins to 3.3V

Hello, I am trying to set two pins on the Cyclone III I'm using (EP3C120F780C7N) to work at 3.3V. I'm developing a custom slave I2C controller and the I2C bus will be 3.3V. I changed the pin ...
Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
11 years ago

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That makes sense so I'm good now.

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Great!

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I'll change over to setting the bust to 'Z' when I have a 1 to send over the I2C bus from the slave. This was a great help and really cleared this up for me!

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You can easily make the change at the top-level of your design. Lets say your outputs are scl_out and sda_out, then the tri-state/low drivers in VHDL are; 


scl <= 'Z' when (scl_out = '1') else '0';
sda <= 'Z' when (sda_out = '1') else '0';

Cheers,

Dave