DFROBOTBeetle -The Smallest Microcontroller for Arduino

The small form factor of this unit made it perfect for the project I was building. It can be powered by two CR2032 button batteries in series so there's no need for a bulky USB powerbank to run it.The program load time from power-on was virtually instantaneous, so that was good too.My sole criticism of this product is that the on-line documentation is not brilliant if you want to take advantage of its Bluetooth capabilities, but a bit of googling solved that.I'd buy it again - and probably will.

The pins are not the standard 2.54mm (0.1") spacing, so this cannot be used with a breadboard or veroboard.Also has some strange propietary bluetooth module that does not work with windows without a specific dongle

Small and powerful, works good easy programme, going have to get more cause they brilliant

Works fine on IOS.Recognised and connected with BLE (not macs pre ~2012), but the data written to and read from the serial/uart isn't correct.With some work (check the DFRobot forums & AT commands!) you can make this function as a HID keyboard, which does work with OSX/corebluetooth.Seems to be very low power draw though, and I have had several of these running for over 24 hours on ~5000mah battery pack.