Failure modes causing damage?


#1

My use case for TinyFPGA is mounting on a breadboard and letting my three- and four- year olds connect it up to random circuits. I’m wondering how worried I need to be about damaging equipment e.g. the TinyFPGA itself or a computer providing it with power over USB?

Especially I wonder about failure modes if pins on the TinyFPGA are shorted or if a 9V battery were connected in an unfortunate way. As in - Is that going to fry my board or my laptop :slight_smile:


#2

You may want current limiting resistors on the I/O pins and maybe diodes to clamp the voltage to 3.3v. There is some built-in protection for the I/Os in the FPGA itself, but I’m not sure they were designed for the abuse a child may wreck on them! :laughing:

The USB I/Os are exposed on the bottom pads of the BX. If you have the BX attached on a way that it can’t come loose, then you should be OK. You wouldn’t want 9v on either of those lines. Your motherboard may or may not protect against that error condition.

Shorting out the power of the BX shouldn’t harm your computer. USB ports are required by spec to have some form of overcurrent protection and that protection would be triggered in the case of a short of the power rails to ground.