AR# 1703: XC7300: Can I use a product term Output Enable in a Fast Function Block (FFB)
XC7300: Can I use a product term Output Enable in a Fast Function Block (FFB)
In XC7300 Fast Function Blocks (FFBs), can output enables be driven by a product term (pterm) output?
FFBs must use FOE nets for all output enables. If you drive an output enable with a pterm equation, the software will map the equation to one of the global FOE nets. To do this it will route the signal out to one of the FOE pins, and back in on a global FOE net. This therefore requires the use of one of the 2 FOE pins.