Open Things
Microcontroller Boards

Openthing 1 ESP-CM3

An ESP32-based compute module to replace the Raspberry Pi CM3

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Openthing 1 ESP-CM3 is a powerful, affordable and accessible Raspberry Pi Compute Module 3 alternative based on the ESP32-S2 microcontroller. It has a range of input/output (I/O) pins, including analog and digital inputs, as well as pulse-width modulation (PWM) outputs. It also includes 2 GPIO expanders to perfectly fit the 45 GPIO Pins of the RPi CM3. They are connected via I2C, and the I2C channel can be changed between I2C-0 and I2C-1 via solder bridges.

Why Use The ESP32-S2 as an alternative?

ESP32-S2 is a powerful and versatile computing device that can easily replace the Raspberry Pi Compute Module 3. At the core of this chip is an Xtensa® 32-bit LX7 CPU that operates at up to 240 MHz, providing plenty of processing power for a wide range of applications. Additionally, it has built-in Wi-Fi and USB connectivity, making it easy to connect to the internet or other devices. It also boasts lower power consumption, which can be especially important for applications that require battery-powered operation.

In contrast, the Raspberry Pi Compute Module requires an operating system, such as Debian Linux or the Raspberry OS, making it hard for a fleet of boards to be managed. Linux is a complex system that requires some effort to keep up to date. With custom firmware for the ESP32-S2 and the right tools you can get everything managed out of the box, to concentrate on the real tasks of your application.

Despite these differences, the ESP32-S2 and Raspberry Pi CM 3 share some similarities. Both devices feature multiple input/output (I/O) pins and protocols like I2C and SPI, which can be used to connect various sensors and other components. Additionally, they both support programming using a variety of programming languages, including C++, Python, and others.

Another key advantage to the ESP32-S2 is that it is available and affordable, while the Raspberry Pi Compute Module is widely unavailable due to a global parts shortage.

Overall, the ESP32 microcontroller board is an excellent alternative to the Raspberry Pi Compute Module 3, offering availability, powerful computing capabilities, and wireless connectivity.

Features & Specifications

Open Source

Openthing 1 ESP-CM3 hardware is fully open source and OSHWA certified. You can find files like board schematics, board layouts and project files, Software for testing the module, BOM etc. in our GitHub repository.

The device comes without any firmware or software primarily because we don’t know your project. Openthing 1 ESP-CM3 can run a variety of operating systems like Zephyr or Micropython, which are easy to use. We also suggest checking out Toit.

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In the Press

Hackster News

"Designed to drop in to existing Raspberry Pi CM3 carrier board designs, this ESP32-S3-powered module is a low-cost alternative."


"The ESP32-S2 is a versatile computing device that can easily replace the Raspberry Pi Compute Module 3."

About the Team

Open Things

Berlin, Germany  ·   open-thngs  ·

My motto is "Open the World" - I believe that a world with open products is a better world. Everyone should have the opportunity to incorporate their ideas and skills into a product to create a thing for everyone. Why only use one brain if we can just let everyone think? That is why I develop resource-saving open hardware for smart solutions.

Mirko Häberlin

See Also

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