SeeedStudio: Motor Bridge Cape:

Docs: http://wiki.seeedstudio.com/Motor_Bridge_Cape_v1.0/
Firmware: https://github.com/Seeed-Studio/MotorBridgeCapeFirmware

Needs uart2 and P8.23/P8.25 from eMMC

uboot_overlay_addr4=/lib/firmware/BB-UART2-00A0.dtbo
disable_uboot_overlay_emmc=1
disable_uboot_overlay_video=1
