Hi all,
I tried to share my experience about how to burn preloader/uboot/OpenWRT image, and then boot from eMMC on BPI-R2...
1.Download flash tool from https://spflashtool.com/
windows: https://spflashtool.com/download/SP_Flash_Tool_v5.1628_Win.zip
linux: https://spflashtool.com/download/SP_Flash_Tool_exe_Linux_64Bit_v5.1520.00.100.zip
2. Install MT65xx drivers for your windows PC. You need to install drivers in order to connect your device properly