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Expansion Dock

Expansion Dock {#expansion-dock}

The Expansion dock is a powerful piece of hardware that simplifies the usage of your Omega. It allows you to power the Omega and communicate with it via serial through the Micro-USB port, and makes it incredibly easy to use the GPIOs and Onion Expansions.

The Hardware

Your Expansion Dock has a 30 pin Expansion Header, allowing you to use all of your Onion Expansions. The Expansion Dock is powered by the Micro-USB port that supplies 5V to the Dock. This voltage is stepped down to the required 3.3V required to power the Omega, and also provides 5V to the Expansions and USB Host port.


The Expansion Dock allows for easy communication via the USB-to-Serial chip located in the center of the board. You've also got a great RGB LED that you can control through the command-line interface.

The reset button, located between the power switch and the Micro USB port, can be used to quickly reboot your Omega, or you can hold it down for a factory reset if your Omega is ever in a bad state.

Connecting an Omega

To connect an Omega to the Expansion Dock, line up the Omega's edges with that of the Expansion Dock's as demonstrated below:

Omega plugged into Dock

Make sure your Omega is pushed all the way down as demonstrated in the picture below:

Omega plugged into Dock

You may need to line up the pins with the holes before pressing the Omega into the Dock.

The Expansion Header

The Expansion Header is a convenient tool that gives you easy access to the Omega's GPIOs, and allows you to connect Onion Expansions directly. The Expansion Header is labelled to show you what GPIO is connected to each section.

expansion header pinout


The RGB LED on the Expansion Dock consists of three LEDs that give you the ability to create RGB colors on the Expansion Dock.

GPIO 17 controls the red LED. GPIO 16 controls the green LED. GPIO 15 controls the blue LED.

The RGB LED is active-low, meaning that setting the GPIO to 0 will turn on the designated LED.

Mechanical Drawings

We've made available a detailed diagram of the dimensions and geometry of the Expansion Dock.

Using the Dock

The Expansion Dock makes it incredibly easy to use your Omega. It let's you easily power your Omega, and use Onion Expansions without any external circuitry required. It also makes sure that you don't accidentally burn out your Omega by supplying too much power.

Controlling the GPIOs

The GPIOs on the dock can be controlled using a number of tools we've included in the Omega firmware. You find more on how you can control the Omega's GPIOs in the article on using the Omega's GPIOS

Controlling the RGB LED

You can use the expled tool to specify the color of the RGB LED. It will use software PWM to drive the three LEDs.


expled <6 digit hex value>

Where the first two digits represent the Red value, the next two represent the Green value, and the last two represent the blue value.


expled 0xf21133

This will set the Red to 0xf2, the Green to 0x11, and the Blue to 0x33.

The LED should now be pink-ish. Try experimenting with other colors!