The BlueNRG-MS is a very low power Bluetooth low energy （BLE） single-mode network processor， compliant with Bluetooth specification v4.1. The BlueNRG-MS supports multiple roles simultaneously， and can act at the same time as Bluetooth Smart sensor and hub device. The Bluetooth Low Energy stack runs on the embedded ARM Cortex-M0 core. The stack is stored on the on-chip non-volatile Flash memory and can be easily upgraded via SPI. The device comes pre-programmed with a production-ready stack image （whose version could change at any time without notice）。 A different or more up-to-date stack image can be downloaded from the ST web site and programmed on the device through the ST provided software tools. The BlueNRG-MS allows applications to meet of the tight advisable peak current requirements imposed with the use of standard coin cell batteries. The maximum peak current is only 10 mA at 1 dBm of output power. Ultra low-power sleep modes and very short transition times between operating modes allow very low average current consumption， resulting in longer battery life. The BlueNRG-MS offers the option of interfacing with external microcontrollers using SPI transport layer.