The latest firmware (v1.7) for the stm32f407 (released in PiZero_GX10_180410_V1.2.img) has changes that makes our software non functional.  If people want to run this source, they need to help reverse engineer it or keep the v1.6 firmware from PiZero_GX10_171229_V1.1.img

I've started reverse engineering it, but am not done yet.  I'll gladly share notes with anyone who's interested.