6. Flash eMMC

Flashing the Banana Pi R4 onboard eMMC with your OpenWrt firmware provides you with a factory reset functionality and avoids relying on the SD card to boot and store your config.

Debug UART

Connect your computer to the router using the USB to TTL UART converter:

GND ⇒ GND

TX ⇒ RX

RX ⇒ TX

ALT

You should now have a new device on /dev/tty.usbserial-10 (/dev/ttyUSB0 on Linux). Open a terminal and connect to the serial port using tio (no configuration required).

user@local

Bash

Copy

tio /dev/tty.usbserial-10
[15:37:50.021] tio v3.6
[15:37:50.021] Press ctrl-t q to quit
[15:37:50.034] Connected to /dev/tty.usbserial-10

Flash NAND

Turn on the router and grab the boot menu. Install the firmware to the onboard NAND.

ALT

Return to the menu and turn off the router. Change the boot jumper to boot from NAND.

ALT

Flash eMMC

Turn on the router and grab the boot menu. The boot menu should now display SPI-NAND.
Install the firmware to the onboard eMMC.

ALT

Return to the menu and turn off the router. Remove the SD card and change the boot jumper to boot from eMMC.

ALT

Turn on the router. The boot menu should now display eMMC.

ALT

You can now disconnect the USB converter. Reboot your router and you should have your OpenWrt firmware up and running. Open LuCi, restore your configuration backup and reboot. Alternatively, you can go through the 5. First Boot steps again.

That’s it!