This small PCB (55×35) is born to be a general purpose solution for building any kind of compact wireless battery powered sensor or actuator based on MySensors, an ATMega328P (Arduino) and a RFM69 or NRF24 radio module.

The main features of the pcb are:

• Small dimensions: 55 x 35 mm
• Multiple power options: 2 x AAA batteries or 1xAAA battery (Rechargeable or Alkaline), 1 x CR2032 battery, standard cellphone charger at 5V through the micro USB port or through Vin and GND pin of the MYSX connector
• Reverse polarity protection (Mosfet Q1) to prevent damages in case of wrong batteries insertion.
• Boost converter (ME2188C33) to increase the battery voltage to 3.3V when necessary
• LEDs for radio traffic and low batteries signaling. All configurable in the firmware.
• Multiple radio module supported: NRF24L01 (SMD and THT) and RFM69.
• Footprint for a reed switch
• MYSX connector v.2.6 that integrates the pins for FTDI and ICSP
• Support for ATSHA204 chip (security and signing)
• Mounting hole for a M2.5 screw

This pcb is very flexible, in fact in the d-diot project it is used for:

• Soil moisture sensor
• Door window sensor