External circuit to fpga

[Altera_Forum]

Hallo 

I'm newbie as user of FPGA DE0-nano.  I want to ask, if connected external circuit to FPGA DE0-nano board, what must to be noted in order to FPGA board aware of destruction ? thank you :)

[Altera_Forum]

--- Quote Start ---   I'm newbie as user of FPGA DE0-nano.  I want to ask, if connected external circuit to FPGA DE0-nano board, what must to be noted in order to FPGA board aware of destruction ?   --- Quote End ---    1. The DE0-nano pins are 3.3V and have no protection for over-voltage. Make sure you only connect 3.3V signals to the I/O headers.  2. Connect the ground on the DE0-nano to the ground on your external circuit so that you have a common reference ground.  3. If your external circuit is powered by the DE0-nano, then make sure not to violate the USB current draw.  Cheers, Dave

[Altera_Forum]

I would like to add# 4. 

# 4. If there are only handful of I/Os, you can use level shifters between external circuits and the NANO board. The level shifters are configurable. for example, ON Semi MC14504B