Getting Started

What you will need

What you need to get started with the balenaFin. All the components required to get started with the balenaFin are available in our Developer Kit.


Any storage variant (8GB, 16GB, 32GB and 64GB) will work for this tutorial. If you don’t have one available, you can order now from the balenaFin Store.

Top Side Bottom Side
Fin mapping top Fin mapping bottom

Micro-USB to USB cable

To flash your Fin with an OS, you will need to connect it to your computer with a USB to Micro-USB cable.

Raspberry Pi Compute Module 3 Lite

The balenaFin supports the Raspberry Pi Compute Module 3 Lite (CM3L/CM3+L). “Lite” means that the module itself has the eMMC socket unpopulated and the traces are exposed via SODIMM-200. This is very important since the standard CM3 has a fixed 4GB eMMC. Instead, with the CM3L/CM3+L, the balenaFin can expose variable storage sizes via its embedded eMMC wired to the CM3L/CM3+L via the SODIMM-200 pins.

Power Supply

The balenaFin Developer kit includes a 5.5/2.1mm Barrel Jack Power supply that can be connected to the Barrel connector on the Fin (see BARREL_JACK on Top Mapping). Any other compatible power supply can also be connected with a Phoenix connector (see PHOENIX on Top Mapping). The negative polarity of the Phoenix connector is labeled on the PCB with a “-” symbol. If using a different power supply from the one included in the Developer Kit, please make sure it can provide 6-24V and at least 12.5W. You can also power the balenaFin from the 5V pins exposed by the HAT connector, 2.5A are required as per the HAT specification.

Assembly set-up

Raspberry Pi Compute Module

Place the SODIMM-200 Raspberry Pi Compute Module in the dedicated socket on the rear of the board (see CM3L/CM3+L_SOCKET on Bottom Mapping). Make sure the two side clips are gripping the module on its dedicated half-circular holes.

RTC coin-cell battery

Place the coin-cell battery in its socket (see RTC_CELL on Top Mapping) with the positive polarity side facing upwards. This step can be skipped if you don’t have a coin-cell available. Keep in mind that any RTC examples will not work properly.

Preparing the balenaFin

In order to flash an OS to the balenaFin, the Fin must be placed into a USB Mass Storage Mode to allow the eMMC storage to be written to. The following proceedure will place the Fin into this boot mode:

  • Before powering on the Fin, connect a USB to Micro-USB cable between your system and the Fin's USB_DBG port.
  • Now, connect power to the Fin, either using the Phoenix or Barrel connector (Do not connect power to both!). Ensure that your power supply is rated between 6-24V DC and at least 12.5W.
  • Next open an eMMC flashing tool such as Etcher (v1.5 or above is required for the CM3+) to instruct the Fin to boot into USB Mass Storage Mode. You may also use Etcher to flash your OS of choice to the Fin.
  • Your Fin should now be in USB Mass Storage Mode, with two red (5V and 3V3) and one green (ACT) LEDs illuminated on the LED STATUS panel.
  • The eMMC storage of the Fin is now mounted and can be flashed. If you are using Etcher, you will see it listed as a Compute Module under the writable devices tab.

NOTE: Make sure that you are running the latest version of balenaEtcher.
NOTE: If you are using a Linux platform, make sure you are running etcher using sudo.

Flashing an OS

This tutorial will be focused on the standalone version of balenaOS 2.x. For more information on balenaOS see “Variants of balenaOS” in the documentation.

After successfully flashing the Fin, ensure to remove the cable from the USB_DBG port before power cycling the board. The Fin should now boot normally, booting into the newly flashed OS.

NOTE: Ensure that your power supply is rated between 6-24V DC and at least 12.5W.
NOTE: Any other recent OS distribution (2018+) for the Raspberry Pi 3 Model B should be compatible with the balenaFin, including Raspbian. we also maintain a preconfigured Raspbian set of images that you can download from here

Getting started with balenaOS

The best way to get started is to connect the Fin to your wireless network and deploy a sample container.

If you are not sure how to do that, head over to the balenaOS documentation on the balenaFin for a complete guide:

Sample projects

Now that you are familiar with loading application containers, let's try using the modules available on the Fin. We put together a repository to get you started with some examples.

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