Waveshare Development Board Kit Expansion Board MISC Cape for Beaglebone Black Rev C 512MB DDR3 4GB 8bit eMMC 1GHz ARM Cortex-A8 Features Miscellaneous Components and Functions for Beaglebone Black further expansion DEBUG interface : for connecting serial modules BOOT selection button : Boot from TF card RTC battery holder : for 3.3V battery RTC power selection jumper