Expansion Boards

Expansion Boards For Microcontroller Projects

Classic breadboards might not always work well for microcontroller projects, especially when using development boards that expose most or all of the microcontroller pins.

Such development boards are often too large to fit on breadboards, or when they do, they occupy almost all usable space.

That’s why for microcontroller projects, specialized expansion boards are used.

Breadboards For Microcontrollers

Expansion boards are highly specific breadboards tailored for specific microcontroller development boards. They must match the microcontroller board that you want to use:

At the heart of the expansion board, there is a socket where you plug in the microcontroller board.

As an added value, expansion boards often include voltage regulators and may be powered from a variety of sources, accepting a wide input voltage range.

Benefits of Expansion Boards

For prototyping, expansion boards are not required but can fix a number of issues:

  • Space As discussed, they target microcontroller boards that are too large to fit on normal breadboards.
  • Power Supply: USB power supply may not be sufficient for projects with many power-hungry components and can lead to brown-outs and unexpected reboots. A more robust power supply provided by the extension board alleviates this.
  • Voltage Range: Most development boards support a very limited input voltage range and can be damaged when exposed to more than 7V. Extension boards often support a wider input voltage range that allows them to be connected to 12V on-board voltage sockets in cars, boats, or RVs.

A few expansion boards even add battery charging capabilities and can become part of the final device.


When selecting an expansion board, make sure…

  • …it is compatible to the microcontroller development board you use
  • …it is configured to supply the correct voltage (3.3V or 5V) to its auxiliary pins (typically controlled by a jumper)
  • …it comes with a built-in voltage regulator powerful enough for your needs.

List of Expansion Boards

Many different expansion boards exist, and it is not feasible to cover them all in detail. Most expansion boards work similarly though, so it’s sufficient to understand what they are and how they are fundamentally configured.

Here is an updated list of expansion boards reviewed so far on this site:

Article Microcontroller Pins Compatible Boards
Review ESP32S 38 DevKitC V4 or similar, width 24mm or 25.5mm

The term ESP32S refers to classic ESP32 microcontrollers like WROVER or WROOM. The term ESP32 is much broader and refers to any microcontroller of the ESP32 family, including WROVER as well as S2 or C3.


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(content created Jul 03, 2024 - last updated Jul 05, 2024)