Forum Discussion
Altera_Forum
Honored Contributor
9 years ago --- Quote Start --- Does exist some option that allows to set all unused outputs to VCC/GND ? --- Quote End --- There used to be, and you should NEVER EVER use this option. Why? Consider the case where you have a board with lots of I/Os connected to external devices, eg., a processor. Now lets say you create a "blinky LED" design that uses the clock and LEDs, and you set all other I/Os as driven to VCC or GND. Q: What do you think happens to your board when you configure the FPGA? A: It powers up ever so briefly before the driver conflicts on the FPGA and the external devices cause the FPGA to get so hot that it is destroyed. Yep, I learnt this one the hard way. The precursor to Quartus (MAX+Plus II) had the default to drive unused I/Os to ground. I repeat NEVER EVER define unused I/Os as GND/VCC! Cheers, Dave