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Mikrotik RouterBoard RB750 r2 hEX Lite


  • currently a specific kernel (3.10.49) with a patch was working (link below), and only squashfs filesystem.

Hardware specification

Spec Comment
CPU QCA9531-BL3A-R 500 Mhz This SoC is currently not supported by OpenWrt
Memory 64 MB -
Flash Winbond W25Q128FV 16 MB SPI-NOR, 4K+0 bytes/sector, 32/64K/eraseblock

FIXME 500MHz is in contradiction to the OEM website (see above), which mentions 850MHz. Since this is higher than the QCA9531 can get, the SoC must also be questioned.tmomas 2016/04/04 21:40

Flash Layout

mtd0 - bootloader mtd1 - kernel mtd2 - rootfs mtd3 - rootfs_data mtd5 - art
mtd5 - firmware
  • serial pins are on the board, you need to put four pins on the board and you need an USB - TTL interface

Netboot OpenWrt

A precompiled ramdisk image is available. Instructions about setting up a TFTP server can be found here. Press the RES button before powering it up, and keep pressing until the LED is blinking then up and down.

Please note that the aforementioned mechanism is not properly working on some boards. Don't worry, bott up the mikrotik board, connect your DHCP client to port 1. And address from must be obtained. You can now telnet to the board, and configure it for TFTPboot.

Telnet user is admin, leave the password empty.

system routerboard settings set boot-device=try-ethernet-once-then-nand 
system routerboard settings set boot-protocol=dhcp 

Now reboot the board, it should boot from port0 now.


  • the bootloader installed (Routerboot) is not loading the kernel properly, needs to be reflashed
  • th bootloader is not initializing the serial PINs so the serial console wont work (until bootloader reflash)


toh/mikrotik/rb750_r2.txt · Last modified: 2016/04/04 21:48 by tmomas