The NRF51822 Bluetooth Smart Beacon Kit is a reference design that lets you explore the full range of development possibilities for beacons using Bluetooth Smart technology. It consists of hardware, firmware and apps for both iOS and Android on Bluetooth 4.0 enabled smartphones. It is ultra-compact at 20 mm diameter and can run from CR1632 coin-cell batteries. The kit has two buttons which can be programmed to enable easy switching between modes and/or functionality, as well as an RGB LED which can be configured to indicate different events. Ten GPIO pins are available for expansion and the kit can be connected to an external programmer/debugger during development work. The nRF51822 Bluetooth Smart Beacon Kit also supports complete Over-The-Air (OTA) Device Firmware Upgrade (DFU) for all firmware on the nRF51822 chip.