Running OpenWrt on Beaglebone Black

The official Openwrt images for Beaglebone Black (BBB) lack some functionalities that many users expect in the default build.

• Network connectivity via the mini USB port.

  • The module g_ether provided by the package kmod-usb-gadget-eth creates a RNDIS compatible USB-to-Ethernet interface (typically usb0) on the device. Note: Windows systems might require (self) signed driver for the Linux USB Ethernet/RNDIS Gadget device to work. Otherwise, you will see only a serial port.
  • The IP address of the usb0 interface is 192.168.100.1.
  • A DHCP server runs on the usb0 interface to allow the USB host device assign an IP address automatically.

• Capability to flash the onboard eMMC storage.

  • This requires accessing OpenWrt terminal via ssh or UART.
  • Use the following command to flash the eMMC storage. Note: Running this command erases eMMC storage!

    root@OpenWrt:~# /lib/functions/mmc_flasher.sh

• Force booting from the external SD card by pressing "User Boot" (S2) button.

  The onboard boot ROM searches for the second stage boot loader (SPL or MLO) in the following order.

  • S2 not pressed - MMC1 (onboard eMMC), MMC0 (SD card), UART0, USB0.
  • S2 pressed - SPI0, MMC0 (SD card), USB0, UART0.

  After the MLO has loaded the third stage boot loader, uBoot (u-boot.img), uBoot reads the boot script (boot.scr) and the boot environment file (uEnv.txt). In most of the builds, uBoot searches for the boot.scr and the uEnv.txt in the MMC0 (SD card) first. This causes the BBB to boot from the SD card regardless of the status of the S2 button.

  We address this problem by reading the status of the S2 button inside the boot.scr to determine the boot device.

• IP address of the onboard Ethernet interface is configured via DHCP instead of static.

• Creating WiFi access points.

  • Requires the packages hostapd-mini, wpa-supplicant-mini installed.

• Support for popular WiFi chips such as "Atheros AR9271".

  • Requires the package kmod-ath9k-htc installed.

Usage

./create-image.sh -h
Script for creating OpenWrt SD card images for Beaglebone Black

Usage: create_image.sh [options] OPENWRT_VERSION
Options:
          -d, --download-dir  Directory for downloaded files
                              Default to ./download
          -o, --output-dir    Directory for created image files
                              Default to ./bin
          -t, --temp-dir      Directory for temporary files