What do you get when you cross an Arduino with a Raspberry Pi Zero? That is a strange question, but stranger still is that we now know the answer, and can hold it in our hands! EspinalLab’s ATMegaZero 32U4 takes the ATmega32u4 microcontroller found in Arduino’s Leonardo board and mixes things up by including the 40-pin header found on Raspberry Pis, as well as incorporating the diminutive form factor of the Raspberry Pi Zero. But is this board more than a freaky mashup inspired by two maker titans?

Part Arduino, part Pi…all easy and expandable!

The first thing that stands out beyond the initial Frankenstien form factor is the quality of ATMegaZero’s documentation and resources. Often with small-batch boards, a unique proposition is stifled by poor documentation or support, but EspinalLab have clearly put a great deal of effort into not making this mistake. Their documentation site features detailed specs, pinouts, setup instructions, and examples. The ATMegaZero uses Arduino’s development environment, making it ideal for beginners, and a custom Board Manager definition means that the 3rd-party board can be used just like Arduino’s own hardware.

No board review would be complete without blinking an LED, but since the ATMegaZero is completely Arduino-compatible, and features a built-in LED on the Arduino standard pin 13, it’s as simple as selecting the ATMegaZero board and port, and running Arduino’s built-in Blink sketch!

Pin parity with Pi

Once you’re ready to move beyond blinky, ATMegaZero’s Learning Shield furnishes three LEDs, a push button, and a buzzer – we used it to create a mini light tree for very tiny cars to use when starting a race! Due to the stackable nature of the ATMegaZero, you can literally grow your board as you grow your skills, with options like the RTC (real-time clock) Shield to help keep time, even when the power’s gone, or the Lipo Shield to give you power on the go. 

The Sensors Shield opens up a whole new world of possibilities, with temperature, humidity, light level, barometric pressure, and air quality sensors, plus a six-axis accelerometer and built-in RTC. Complete your stack with the Relay Shield, and control four external devices, up to 220V/10W. Then top it off with the available OLED display, which takes advantage of the ATMegaZero’s built-in display port (opposite the microSD, where a camera port would ordinarily be found on the Raspberry Pi Zero), and an ESP-01S ESP8266 Wi-Fi module to get your device online.

Stack ’em if you got ’em!

Beyond the selection of shields offered by ATMegaZero, the 40-pin form factor also provides compatibility with some Raspberry Pi HATs and pHATs. Since the board is 5V, unlike the Pi’s 3.3V, this reduces the pool of usable hardware, although there are still a number of available options. One great example is Pimoroni’s Scroll HAT Mini, which matches the Zero form factor and provides a bright 17×7 charlieplexed LED display for scrolling text or animations. In addition to logic level, compatibility is often hindered by software incompatibility, given that the ATMegaZero is an Arduino-compatible microcontroller, whereas the Raspberry Pi is a Linux-based single-board computer. Thankfully ATMegaZero provide a wide selection of their own shields, which are guaranteed to work with the 32U4.

ATMegaZero 32U4 with 5V-compatible HAT

While it may seem counterintuitive, this Raspberry Pi-looking board is actually a great way to get started with Arduino! Excellent documentation, its own ecosystem of expansion boards, and the potential ability to go beyond its native capabilities with 5V Raspberry Pi HATs and pHATs means that ATMegaZero is not just a great way to get started, but a great platform for prototyping and building any number of projects.

The ATMegaZero 32U4 literally grows with your skills

Standout features: 

  • Raspberry Pi-compatible header pins
  • Rich ecosystem of ATMegaZero-designed shields and broader Pi-compatible pHATs
  • Great documentation and examples