Here's a new STM32F4 Core:     It has most of the functionality of the Discovery one, but has a few improvements: USB ports are on the breakout, so there's proper USB B USB A "host" - still need to test this, but it's normally done setting the ID pin low. I've put a panel switch for selecting host/slave and there's a jumper to power the slaved device if needed. LEDs and reset button on the panel; "blue button" as a jumper a 3.5mm socket for a