RTOS Based Data Logger Using BLE Periodic Advertising for Cold Chain Temperature Monitoring

In this paper, design of a BLE periodic advertising based data logger for cold chain temperature monitoring has been proposed, which is implemented using multi-threading on a Real Time Operating System for smooth, unhindered operation. The low-power logger design only implements the data fetching, storing and transmission operations, and the logged data can be accessed on a smartphone app using BLE periodic advertisements, through a simple button press, as many times as required to achieve 100% reception in the app. The data processing capabilities are implemented in the smartphone app and not the device to save power. Data transmission consumes ultra low current by the use of BLE periodic advertisements, which are experimentally shown in this paper to consume an average current of only 99.3 µA for transmitting the data logged over 24 hours. Additionally, even without entering into a connection, the data reception using BLE periodic advertising has been experimentally found to be in the range 96–98 % due to its ability to synchronize with the receiver, and the use of secondary advertising channels for data transfer. We have developed a smartphone app that implements a BLE periodic scanner, and allows the user to successfully receive 100% of the logged data, save it to the device/cloud and export the data anomalies based on the ambient range of values provided.