The SENSOR-PUCK provides a convenient development and demo platform for Silicon Labs' Si114x optical sensors and  Si701x/2x relative humidity and temperature sensors. The coin-cell battery operated SENSOR-PUCK is controlled by an EFM32™ energy friendly MCU. A Bluetooth Low Energy (BLE) module is used to broadcast sensor data to iOS or Android smartphones with the downloadable SENSOR-PUCK app. Place your finger tip over the Si1147 sensor to measure heart rate. Environmental sensing of UV Index, ambient light, relative humidity, and temperature is also provided. For power management, the board features a Touchstone TS3310 boost DC/DC converter.

Features

Environmental mode

• Measures ambient light, UV index, ambient temperature, and ambient humidity.
• This is the default mode of operation and the lowest power.
• In this mode of operation measurements are taken and broadcast (once per second).
• The LED flashes green once per measurement cycle.
• The battery current consumption in this mode is approximately 1.5 mA average, which means that a standard CR2032
battery will last about five days. The battery for this demo is not rechargeable so it must be replaced if it is depleted.

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).
• If an object is detected the puck will go into biometric mode and attempt to measure heart rate.
• Heart rate is measured by the reflection of IR light from an LED inside the Si1147-M01.
• The light is reflected from a finger-tip to measure the heart rate.
• In biometric mode the power consumption goes up to 7 mA, so battery life will decrease to about one day in this mode.
• In biometric mode, the LED will flash red while it is acquiring the heartbeat and then switches to continuous green once the heartbeat has been acquired.
• To avoid excessive power drain in case the puck is left on and covered with an object, the puck will exit biometric mode after 90 seconds. In this case, the object must be removed and a finger should be placed over the acrylic cover to start biometric monitoring again.
• 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. For this reason, it possible that a single mobile device (i.e. a phone) can display data from multiple pucks.