MYSENSORS MICRO (Itead IM150321002) NRF24L01+ 

The MySensors Sensebender Micro is a tiny Arduino compatible board stackable with a Nordic NRF24L01+ transceiver module. The Micro has been designed for extended battery life; e.g. it operates at 1Mhz without the need for power regulators for low power consumption. Even in its small form factor it's packed with great features such as temperature and humidity sensor, 64k extra flash memory and a hardware module for secure message signing and verification. Need more? Expand the functionality by attaching additional breakout sensors to the five digital GPIOs, two analog inputs or the I2C interface. The full documentation is available athttp://www.mysensors.org/hardware/micro

About MySensor

MySensors.org is a community-driven Open Source project for the Do-It-Yourself Home Automation enthusiast. MySensors provides easy-to-follow hardware assembly instructions and ready-to-use source code examples that opens up a whole new world of custom made sensors and actuators. The project allows you to control your things and collect sensor data using your favorite home automation controller. The sensors automatically create a reliable mesh communication network using repeater nodes for extended range applications.

Technical Specification

• Very small footprint, 30 mm x 17.5 mm (1.18in x 0.69 in). Making it almost same size as the NRF24 module.
• Arduino IDE 1.5.x & 1.6.x compatible. 
• Si7021 integrated humidity / temperature sensor. 
• 64kb SPI flash / e2prom onboard. Useful for over-the-air firmware updates. Also possible to use memory for a local sensor data cache. 
• ATSHA204A on board (connected to A3). Used for SHA256 key exchange and verification. 
• Runs directly off 2x1.5V batteries (AA or AAA), without power converters. 
• Socket* for connecting the radio module on top. 
• Pin-headers* for D3-D7 on one side, and SDA/SCL + A0/A1 and power on the other side. 
• FTDI header similar to Arduino Pro Mini. 
• Standard Atmel programming ISCP header. 
• Pads for mounting a 32Khz crystal (when timing is crucial). 
• Status LED (on A2).

* You have to solder the radio socket, and pin-headers yourself

Note: The actual NRF24L01+ module is sold separately.