The M3 is not well documented. The big thing to discover is the memory map to get at the IO. At least the firmware is open source to help provide a starting poi

The M3 is not well documented. The big thing to discover is the memory map to get at the IO. At least the firmware is open source to help provide a starting point and it includes some base addresses for peripherals in the system. https://e2e.ti.com/support/arm/sitara_arm/f/791/t/284956 https://e2e.ti.com/support/arm/sitara_arm/f/791/t/284956 http://arago-project.org/git/projects/?p=am33x-cm3.git;a=summary http://arago-project.org/git/projects/?p=am33x-cm3.git;a=sum... http://www.ti.com/lit/ug/spruh73o/spruh73o.pdf http://www.ti.com/lit/ug/spruh73o/spruh73o.pdf page 1172