How does SW4 affect on booting?

Hello, What influence has SW4 on booting? Thank you, Michał.

I’ve found, that:

  • if it is off (0), board boots from EMMC
  • if it is on (1), board boots from SPI flash, and in this case, whed SD card is inserted, it is detected and SPI loader wants to boot from SD, but card layout is unknown. If SD isn’t inserted, board boots to LittleKernel and LK’s shell is started.

Question for BPI staff – what ls a layout of bootable SD card?

My board boots from SD card only in SW4’s position 0

Strange, I’ve seen no difference booting with SW4=0 when SD is inserted or not. It always boots Android from EMMC.

BPI W2 boot with SW4=1 and SD inserted -

BPI W2 boot with SW4=0 and SD inserted -

BPI W2 boot with SW4=0 and no SD inserted -

And I see no way to boot from SD directly

please refer to