This week’s EYE ON NPI (video) will pique your curiosity… it’s Microchip’s AVR-IoT Cellular Mini Development Board, featuring the Sequans Monarch 2 GM02S cellular module.
This dev board really knows how to get us interested with an AVR128DB48 128KB-flash AVR chip, Sequans GM02S compact LTE cell module, Feather format, Stemma QT / Qwiic connector and Arduino library support. This is an excellent dev board to use if you want to take advantage of the huge ecosystem afforded by Arduino, Feather, Qwiic/QT – you should be able to use the many thousands of libraries and hardware accessories for quick prototyping.
As mentioned, this dev board is Feather shaped, with a USB Type C connector, Li-poly battery charger, and built in programmer/debugger/serial interface for the AVR chip.
The individual microcontroller is a AVR128DB48 AVR, which comes with 128KB flash and 16KB RAM. Think of it as a super-beefy ATmega328P! A SAMD21E ‘curiosity’ chip is used as the programming interface and also serial interface. When plugged in, the board shows up as a disk drive, with a getting started guide bookmark and some other specification files. While following the getting started guide, we found that you can also drag hex files over to program it, very handy for quick-start! To program it, MCP suggests using the DxCore from SpenceKonde in Arduino, so you’ll want to get that installed while you follow the rest of the guide.
Next up, time to activate the included SIM card from Truphone that comes with the dev kit. This SIM is free to activate and is good for up to 150 MB of data transfer and 90 days, which is plenty of time to explore the board before needing to renew. Activating the SIM only took us 5 minutes – don’t forget to power cycle after activation to make sure the module and SIM re-authorize.
One of the surprises we had while trying this eval board is the really good documentation and learning system that is over at https://iot.microchip.com/avr-iot-cellular-mini – we’re kinda used to verbose text-based documentation or using specialized software that only runs on Windows. This is the first time we’ve seen a really nice documentation system with simple step-by-steps, lots of photos, links and a clear navigation system. There are also two interesting in-browser compilation and serial monitor widgets that we spotted, which is a good sign that folks are starting to move towards browser-and-filesystem replacements for toolchains.
The Arduino library code is available over at https://github.com/microchip-pic-avr-solutions/avr-iot-cellular-arduino-library which looks like it’s got platform.io support and you can download a release for installation into the Arduino IDE. (We do recommend someone at MCP try to add a proper release to the Arduino library manager to save one extra step if possible!) Once installed, there are a few helpful examples to get you going. The first one is just connecting to an HTTP endpoint and parsing out the result and it worked…really well! We were able to connect to the AT&T cellular network and fetch the data within a minute. We’d request an HTTPS example, since most folks will want a TLS method of connection!
Since the board is Arduino and Stemma QT compatible, we were able to connect an OLED and extend the example to display the HTTP-gotten data to the OLED – it only took us 10 minutes to install everything for Arduino library support and extend the code, which is amazingly fast!
You know what else is really fast? Digi-Key shipping for the AVR-IoT Cellular Mini Development Board, cause it’s in stock right now! Order today and you’ll be connecting to the LTE cellular network by tomorrow afternoon.
The approach of putting an interactive web site on a USB MSD on the dev board is really interesting. Wondered if there was any thought of supporting this in CircuitPython? Obviously we can put static web pages on the CIRCUITPY drive, but there is no obvious way to communicate between JavaScript in the web page running in a browser and CircuitPython code running on the chip.