“In this project, we build an economical and full-featured Bluetooth Low Energy (BLE) data logging system that takes readings from multiple sensors and saves the data to an SD memory card. A data logger is an integral part of environmental monitoring with wide application. Essentially, the logger reads sensor data and records the readings over time. In our project, the sensor array for the data logger is provided by a TI SensorTag that operates as a battery-powered BLE peripheral. To read the SensorTag, we use an Arduino 101 operating as a BLE central device. To log the sensor readings, we use the Arduino 101, along with an SD shield, to write the time-stamped sensor data to a standard Secure Digital High Capacity (SDHC) memory card (up to 32 GB) that can be read by multiple computer systems.”