If you are familiar with Arduino boards, the Button Size Node is an Arduino Pro-Mini with on-board HopeRF RFM69-CW/HCW 433/868/915 MHz radio, external EPROM flash, and a crypto authentication chip. To reduce the board dimensions the Button Size Node does not have an onboard USB-Serial converter. You need to buy FTDI Adapter for programming. The HopeRF RFM69-CW/HCW provides an extremely good range. Hundreds of meters in open areas. An external flash chip allows burning Arduino sketch wirelessly. The onboard Atmel ATSHA204A CryptoAuthentication chip secures communication with other controllers.

Some IOT ideas based on the switch node and similar controllers plus complete specs you may find here my my GitHub page

Best suitable for Home Automation, IOT. Could be used as core board for controlling any DIY project. You may think of it as Arduino Pro Mini plus all the items in the picture below:

Specifications

• Dimensions 42.2mm x 20.9mm
• Sleep current consumption 10-12uA
• Temperature and humidity sensor Si7021
• High Accuracy Temperature Sensor ±0.4 °C (max), –10 to 85 °C
• Precision Relative Humidity Sensor ± 3% RH (max), 0–80% RH
• Light sensor BH1750, spectral responsibility is approximately human eye response.
• Authentication security - Atmel ATSHA204A Crypto Authentication Chip
• External JDEC EPROM
• Dualoptiboot bootloader. Implements over the air (OTA) firmware update ability
• RFM69-HW (high power version) or CW (low power consumption version) 433 MHz Radio transceiver
• Battery voltage sensor (via divider)
• Supply voltage up to 6.5 Volts
• The Digital and Analog pins are 3.3 volts
• Battery connector CR2032 240mAh
• FTDI header for programming
• You can cut with scissors, sensors and battery holder part, if you need just controller and radio

RFM69 Versions to choose from

• RFM69 CW 433 Mhz radio
• RFM69 CW 868 Mhz radio
• RFM69 CW 915 Mhz radio
• RFM69 HCW 433 Mhz radio
• RFM69 HCW 868 Mhz radio

Pin outs

Arduino IDE Settings

For schematics lovers

PDF of the board's schematic