Introducing RabbitMax Flex Raspberry Pi HAT

More than six months ago I started a small hobby open source project and today I am happy to announce RabbitMax Flex – a general purpose Raspberry Pi HAT for rapid prototyping of Internet of Things.

For those of you who are not familiar with the fancy term Raspberry Pi HAT, it is just a standard add-on board for Raspberry Pi with dimensions 65x56mm, a 40 pin female header and a device tree overlay saved in an EEPROM.

RabbitMax Flex Raspberry Pi HAT has a relay, a button, a piezo buzzer, a RGB LED, an infrared receiver and an infrared transmitter. The best feature is that you can attach up to 5 sensors and a character LCD display module.

So far the officially supported sensors are for:

• Temperature and barometric pressure (BMP180)
• Temperature and humidity (HTU21)
• Light (BH1750)

Of course you may also attach any other I2C sensors but you will have to take care of their software integration.

RabbitMax Flex is compatible with any Raspberry Pi models and versions with 40 pin headers. This is the full list of supported Raspberry Pi models and versions:

• Raspberry Pi 3 Model B
• Raspberry Pi 2 Model B
• Raspberry Pi 0
• Raspberry Pi Model B+
• Raspberry Pi Model A+

Please note that RabbitMax Flex is NOT compatible with the earlier 26-pin models of Raspberry Pi 1 Model B & A's.

RabbitMax Flex has been tested using Raspbian - the most popular GNU/Linux distribution for Raspberry Pi. It should work with any other GNU/Linux distributions too. The hardware was been developed using the free and open source electronics design automation suite KiCAD.

Getting started is super easy. You can assemble RabbitMax Flex to your Raspberry Pi with your bare hands. After that you can mount up to 5 I2C sensors and the LCD display module. Adjust the brightness of the back light of the LCD display module through the potentiometer using a screwdriver. Visit rabbitmax.com and explore the user's manual for details.

Open source examples for all built-in peripherals and supported sensors are available in GitHub. They are written in Python and the C programming language.

There is an EEPROM on the right upper corner of RabbitMax Flex. It contains a device tree overlay with a description of the hardware of the HAT. This feature is very useful for advanced users and software developers because the information can read from the software after booting Raspberry Pi with the HAT.

RabbitMax Flex is a Raspberry Pi HAT suitable for existing Raspberry Pi customers interested in home automation, software development and Internet of Things. The board is appropriate for embedded programming enthusiasts, GNU / Linux gadget fans, students as well as web and mobile app developers. The main usage of the board is embedded software development without the urge of understanding perfectly the hardware.

RabbitMax Flex is convenient for various use case such as a weather station, a desk assistant or an automated infrared control of TV, hi-fi, air conditions and other home appliances. Furthermore the relay makes it appropriate for do-it-yourself (DIY) home automation. Now I am working on a GNU/Linux distribution built with the Yocto Project and OpenEmbedded specially for RabbitMax that will simplify the usage of the HAT and will allow remote access through the lightweight communication protocol MQTT and an user friendly web interface.

A small batch of RabbitMax Flex is on sale Tindie. Now I am preparing an IndieGoGo campaign and I am trying hard to reduce the manufacturing costs and the end product price.