Environmental and Biometric Sensor Puck with BLE
Created: Feb 15, 2017
No description available.
Integrated devices are the most common progress in electronics today. With compact and multiple sensors are being added to form one unit of high-end devices. The reference design is a sensor puck from Silicon Labs that broadcast results without any established connection, making it available to several modules at the same time. The design features (Si1147-M01) optical sensor, temperature sensor (Si7021), and low power MCU (EFM32G210 “Gecko”). To display the results of the design, Silicon Labs Sensor Puck application must be installed to mobile devices.
The sensor puck can operate in environmental mode and biometric mode. The CR2032 battery is used to power most of the ICs. A boost converter is used to produce 4.1V which is used to power the LED of the Si1147 so it can be driven at higher current than is possible with a coin cell battery. In environmental mode measure the ambient light, UV index, ambient temperature, and ambient humidity. In this mode of operation measurements are taken and broadcast (once per second) and it operates on lowest power. The LED flashes green once per measurement cycle and the battery current consumption in this mode is approximately 1.5mA average. In biometric mode, at the once per second interval for environmental monitoring, the puck checks for the presence of an object over the Si1147-M01 (under the acrylic cover). When an object is detected the puck will go into biometric mode and will attempt to measure the heart rate using the reflection of IR light from the LED inside the Si1147-M01. In biometric mode the power consumption goes up to 7mA. The LED will flash red while acquiring the readings and switches to continuous green when it is done. The data from the puck is broadcast over a BLE “advertisement” packet. The mobile device that displays the data does not need to make a connection to the puck.
The sensor puck application can be installed to Android devices version 4.3 and higher, and has a bluetooth 4.0 hardware. Some basic android devices are Samsung Galaxy S4, Samsung Galasy S5, Samsung Galaxy Tab 3, Motorola Moto E, Motorola Moto G, HTC Desire, HTC One Max, LG Nexus 5, LG G Flex, Sony Z1, Sony T2 Ultra, and Asus Nexus 7.