The GPIO output pins on Intel® Galileo are provided by an I2C Port Expander that is running at standard mode (100 kHz). Each I2C request to update a GPIO requires approximately 2ms. In addition to software overhead, this restricts the frequency achievable on the GPIO outputs to approximately 230 Hz.
Oh crap! Well there goes that idea.
230 Hz (or even 500 Hz) is just way too slow.
Considering that AVRs can toggle at several hundred KHz that is simply unacceptable.
Out of curiosity, how does the GPIO speed compare to something like a Raspberry pi