Measuring a tiny 1.4" long by 0.7" wide, the Adafruit ItsyBitsy M4 Express is “smaller than a feather” and features an ATSAMD51 Cortex M4 microprocessor running at 120MHz. With six power pins and 23 GPIO (seven are optionally analogue in, with 2 x 1 MSPS analog out DACs, and 18 x PWM out), the board also comes with 2MB of SPI flash, for logging, running CircuitPython code, or storing data. The 32-bit board also has a hardware digital signal processor (DSP) with floating point support, 512KB flash, and 192KB of RAM, and can be powered via a suitable USB adaptor.
Why is it so small? Well, not every project has to be limited by the size of your existing board. Thanks to the Adafruit ItsyBitsy M4 Express being compatible with Arduino IDE, you could develop a project on your existing Arduino (or ItsyBitsy) and shrink down. When connected to a computer, the Adafruit ItsyBitsy M4 Express will appear as a small disk drive, featuring a single file called main.py, which can be edited to build your project code.
Any device can read this file, and the Adafruit ItsyBitsy M4 Express doesn’t require a driver to connect; as such, you might edit code on a Chromebook, a locked down PC that doesn’t let you install software, or even on a mobile device with USB OTG support.
While it’s not the smallest, the Adafruit ItsyBitsy M4 Express is nevertheless an excellent little board that comes pre-tested. Bundled in are three GPIO headers that you can solder in place, if desired.
You can buy the Adafruit ItsyBitsy M4 Express for just $14.95.