User Manual


What is OOWOW?

OOWOW is an embedded service (integrated into your device) - it can be run at any time if you need to perform essential maintenance services on your device.

About VIM4

VIM4 is the first device from Khadas that includes the OOWOW embedded service. Since VIM4 comes without any pre-installed OS, users can use OOWOW to select and install their preferred OS.

OS Delivery

OOWOW provides rapid online OS download and installation, which will improve quality of life for single board computer users - with OOWOW, you can install / reinstall your preferred OS in just 2-3 minutes.

OOWOW Wizard

The OOWOW wizard will guide you to install a new OS in just 4 steps, and it automatically starts if your device storage is empty.

  • Connect to internet over Wi-Fi or Ethernet
  • Display OS images for your device
  • Select OS installation image
  • Download and install OS into your device

Wizard Usage Example:

Tip: If you need other features, exit from the wizard to the main menu.

Main Features

  • Install / reinstall OS
  • Download online OS images
  • Backup and restore system
  • Display full device information
  • Configure device
  • Device hardware testing
  • Online script collection
  • Rescue shell
  • Developer and advanced features


Hardware Buttons

You can use the three physical buttons on your device to interact directly with the OOWOW system, we will describe them in more detail within the next section.

  • RESET - reset device
  • FUNCTION - multi functions
  • POWER - multi functions

VIM4 Button Shortcuts

  • Boot OOWOW - hold FUNCTION and short press RESET then release FUNCTION
  • Toggle Easy Wi-Fi - short press POWER button
  • Toggle Hotspot - short press FUNCTION button
  • Accept Hotspot client - short press POWER button
  • Power off - Long press the POWER button until device shuts down
  • Enter multifunction mode - press and hold FUNCTION button (loop cycle: Hotspot -> Firewall Allow -> Firewall Block -> Cancel, each mode wait 2 sec ), release to activate selected function

Tip: All shortcut events will be displayed on OOWOW status bar and indicated by LEDs.

Tips to Boot OOWOW

  • Eject your TF card before booting OOWOW (TF card has highest priority)
  • Boot OOWOW from sleep: hold FUNCTION button + short press RESET button + release FUNCTION button
  • Boot OOWOW with power cable: hold FUNCTION button + plug power cable

LED Indication Table

Most system events have corresponding LED indications:

  • Device starts or reboots: White solid
  • Device power off: Red solid
  • System start in default mode: White heartbeat
  • Network connected: White solid
  • Hotspot mode activated: White fast blinking
  • Hotspot mode ready: White solid
  • Hotspot client pending: White and red blinking
  • Hotspot client accepted: White slow blinking
  • Hotspot mode deactivated: White heartbeat
  • Easy Wi-Fi activated: White blinking
  • Easy Wi-Fi awaits connection: White slow blinking
  • Easy Wi-Fi deactivated: White heartbeat
  • Firewall block incoming: Red breathing
  • Firewall allow incoming: White solid, red off
  • Firewall disabled: Red blinking
  • Image installation progress: Red & white blinking
  • Image installation done: White solid, red off

Multifunctional modes:

  • Hotspot: White off
  • Firewall block incoming: White solid, red off
  • Firewall allow incoming: White & red solid
  • Cancel: White blinking


Main Menu

OOWOW provides a universal user interface (terminal mode menu + top status line) for HDMI, WEB, SSH, Serial-UART, etc (all interfaces work simultaneously)


  • Keys: 0-9 A-Z ⇦ ⇨ ⇧ ⇩ Space Enter Esc Tab
  • Mouse: select menu items and press buttons

HDMI + Keyboard

A HDMI screen and keyboard is the primary interface modality.

Web Access


Tip: Access can be restricted by the Firewall.

Mobile Navigation

  • Keys: 0-9 A-Z Space Enter
  • Touchscreen: select menu items and press buttons
  • Some virtual keyboard have additional keys: ⇦ ⇨ ⇧ ⇩ Esc Tab

SSH Access

  • root access works by default without password
  • ssh root@vim4-xxxxx.local - plain shell
  • ssh root@vim4-xxxxx.local system - main menu

Tip: Access can be restricted by the Firewall.

Serial UART Access

For developers and advanced users only.

  • Check documentation to setup the serial debug tool
  • root access works by default without password
  • system - main menu


For developers and advanced users only.


Network connection is required for:

  • OS downloading and installation
  • OOWOW system updates
  • Dynamic syncing of online scripts
  • Remote control over LAN and WLAN

Device Network Name

Every OOWOW device can be accessed remotely via its unique LAN name.


  • device: lowercase device name, e.g. VIM4 -> vim4
  • xxxxx: last 5 digits of the device serial number

Network name examples:

  • vim4-00010
  • vim4-00012
  • vim3-12333

Network Name Resolution

Depends on your LAN configuration, for example:

  • vim4-00010 - dns resolver
  • vim4-00010.local - umdns resolving - canonical variant for OOWOW


  • Use device ip address if name resolution doesn’t work.
  • OOWOW uses the DHCP hostname.
  • OOWOW uses the MDNS hostname announcement.

Network Name Usage Examples

# ping vim4-05690
PING vim4-05690 ( 56(84) bytes of data.
64 bytes from ( icmp_seq=1 ttl=64 time=37.3 ms

# ping -c1 vim4-05690.local
PING vim4-05690.local ( 56(84) bytes of data.
64 bytes from ( icmp_seq=1 ttl=64 time=37.3 ms

# curl http://vim4-05690.local
# curl
# curl
# ssh root@vim4-05690
# ssh root@vim4-05690.local

Ethernet LAN

Ethernet works automatically; just plug in an ethernet cable from your router.

Wireless LAN

User can setup and configure a WLAN connection
Network -> Wi-Fi -> Wi-Fi Select Connection.


  • Wi-Fi configurations are automatically saved and will persist after rebooting.
  • All system configurations will be saved only after a planned shutdown. Check animation.

Easy Wi-Fi

In cases wherein you are unable to configure a WLAN or LAN connection locally on your device, you can share your internet connection from a mobile device (e.g. smartphone) to your single board computer using the Easy Wi-Fi mode.

You can enable the Easy Wi-Fi mode on your device in two ways:

  • Toggle Easy Wi-Fi - short press POWER button
  • Network -> Wi-Fi -> Easy Wi-Fi oowow > Enable / Disable

Setup a new hotspot from your mobile device with the following configuration:

  • SSID: oowow
  • Password: 12345678

Once OOWOW is in the Easy Wi-Fi mode, it will automatically scan and connect to your Wi-Fi hotspot generated by your mobile device.


You can enable the OOWOW hotspot feature in two ways:

  • Toggle hotspot - short press FUNCTION button
  • Network -> Hotspot -> Hotspot Enable / Disable

The OOWOW hotspot will have the following configuration:

  • SSID: vim4-xxxxx ( xxxxx - last 5 digits from device serial number )
  • Password: 12345678

These hostnames can be used for device access via the hotspot:

Tip: For security reasons, you need to manually accept incoming hotspot connections by short pressing the POWER button once.

Hotspot QR code

Network -> Hotspot -> Hotspot QR code.

Web access QR code

  • Network -> Hotspot -> Device Web Access QR code
  • Network -> Wi-Fi -> Device Web Access QR code

USB-OTG Network

Connect your device directly to your computer using a USB cable. This feature will interest developers or advanced users; there is only a peer-to-peer network connection, no internet packets will be forwarded to your device.


Network -> Firewall Mode:

  • block - Block all incoming connections SECURE
  • allow - Allow incoming connections from local networks RECOMMENDED
  • disabled - Allow all connections, firewall disabled DANGER


  • By default, remote access is blocked by the firewall
  • Easily configure the firewall with the hardware button shortcuts
  • ICMP pings are always allowed, irrespective of firewall mode
  • Hotspot mode allows incoming connections only after pressing the POWER button (device access: or
  • USB-OTG connection is always allowed

Usage Examples

Configure Wi-Fi with Wizard

Check here.

Wi-Fi Connection

Check here.

Easy Wi-Fi Connection

Check here.

Hotspot Mode

Check here.

Hotspot Mode + Ethernet LAN

Internet access provided by LAN ethernet cable, user device access provided by WLAN hotspot.

Hotspot Mode + Wi-Fi WLAN Connection

Internet access provided by WLAN wifi-connection and user device access provided by WLAN hotspot same time.



Security and Privacy

  • OOWOW works only by user demand, and never works in the background
  • OOWOW never sends any private data from your device to the internet
  • By default, remote access to your device is blocked by the firewall


  • Unicode international symbols don’t display properly for HDMI (Wi-Fi network names)
  • IPV6 disabled at this time


  • Automatically looks for updates when internet is connected, user will be notified if new updates need to be applied
  • System updates must be manually approved by the user
  • Don’t turn off computer - during update

Download OOWOW

Check here for oowow system images.

Image Types

  • vim4-oowow-latest-sd.img.gz - latest oowow image for SD-card or USB-thumb drive
  • vim4-oowow-latest-spi.img.gz - latest oowow image for SPI-flash
  • vim4-oowow-latest-spi-upgrade-sd.img.gz - upgrade oowow SPI-flash firmware from SD-card

Filename for Latest OOWOW Version

  • vim4-oowow-latest-sd.img.gz -> versions/vim4/vim4-oowow-VERSION-sd.img.gz

Tip: Download the latest OOWOW image file with this link:

Download images using command line:

  • curl -JOL
  • wget --content-disposition


Why Create OOWOW?

The process of new OS Installation is the biggest headache for users of single board computers (SBC); before installing an OS, users must read tons of manuals, trawl through online forums, learn how to install/reinstall using their desktop/laptop PC, learn where to find proper images etc…If something goes wrong it is possible to “BRICK” (destroy) your device(even through we can use TST mode to recovery rhe device).

In other words, any form of device upgrade, maintenance, or OS reinstallation requires advanced skills and external hardware, and this is out of reach for the average user, or users in regions without desktop/laptop PCs. With OOWOW your SBC becomes a standalone device; perform all maintenance functions and OS installation directly from the device itself.

OOWOW understands the end user deeply; it provides an out-of the-box, universal OS delivery and device configuration solution for all SBCs in the market today and into the future.

Live life easily with OOWOW!

What is the meaning of ‘OOWOW’?

oowow - infinity level wow (will be a new 77th word in the English dictionary).

  • Pronunciation: /uː/ + /wau/ = /u:wau/
  • Variations: ∞wow, infinity wow, endless wow