Silicon Laboratories Biometric EXP EVB UG User Manual

Biometric EXP EVB UG

BIOMETRIC EXP Evaluation Board USER’S GUIDE

1. Introduction

The Silicon Laboratories’ Biometric-EXP Evaluation Board is a hardware plugin card for EFM32™ Starter Kits
(STK’s). The Biometric-EXP is intended to demonstrate and evaluate the biometric applications of Silicon
Laboratories Si7013 Humidity and Temperature Sensor and the Si1146 Proximit y/UV/Ambient Light Sensor which
is capable of monitoring pulse rate and oxygen saturation (SpO2). A Biometric-EXP Software Demo is available to
download to an EFM32 Wonder Gecko STK through Simplicity Studio. The software is capable of displaying
humidity, temperature, UV, pulse rat e, and SpO2 readings on the Wonder Gecko STK display. In addition to the
Silicon Labs sensors, it is also of note that the Biometric-EXP EVB contains a Silicon Laboratories’ TS3310 Boost
DC-DC Converter.

Figure 1. EFM32 Wonder Gecko STK (Left) Connected to a Biometric-EXP (Right)

1.1. Key Features

Si7013 Humidity and Temperature Sensor
Si1146 Proximity/UV/Ambient Light Sensor capable of monitoring Pulse Rate and SpO2
6-pin ribbon cable connector for attaching a wrist-based heart rate monitor EVB (ordered separately as

HRM-GGG-PS)

20-pin expansion header
Battery operated with low power optimizations for long battery life
Demonstration software source code available
USB debug mode allowing HRM and SpO2 samples to be transferred to a PC
Windows GUI to visualize pulse signals and to record samples from USB debug mode
Easy use through Simplicity Studio

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Biometric EXP EVB UG

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2. Loading the Demo onto the Wonder Gecko STK

The following steps will load the demo firmware onto the Wonder Gecko STK. This process requires Simplicity
Studio which is available for download at www.silabs.com/simplicity-studio.

1. Connect the Wonder Gecko STK to the PC via USB.

2. Launch Simplicity Studio.

3. Open the Simplicity IDE

Figure 2. Simplicity Studio

Figure 3. Simplicity IDE

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Biometric EXP EVB UG

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4. FromtheSimplicityIDEtoolbaropentheflashprogrammer( icon).

Figure 4. Flash Programmer Dialog

5. Ensure that the Wonder Gecko STK appears in the Device description at the top of the Flash Programmer
dialog.

6. Browse to the hex file EFM32WG_Biometric_EXP_Demo.hex then click Program.

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Biometric EXP EVB UG

3. Running the Demo

A Silicon Labs EFM32 Wonder Gecko Starter Kit (EFM32WG-STK3800) and a Silicon Labs Biometric-EXP (see
Figure 1) is needed to run the Biometric EXP Demo.

The Biometric-EXP demo application uses the Wonder-Gecko STK’s LCD to display sensor output and the two
push buttons, PB0 and PB1, to cycle through the modes of the demo. The full operation including startup is
illustrated in Figures 5 and 6.

3.1. Demo Startup

Upon reset, the demo will first check whether PB0 is pressed then store the result. It will then search for a
supported device on the 6-pin ribbon cable connector. If a HRM-GGG-PS, Si1143-M01-PS or Si1147-M01-PS is
detected, the demo will automatica lly use that device for HRM measurements. In this case, the Si1146 sensor
onboard the Biometric-EXP will not be utilized. SpO2 is not available with either the HRM-GGG-PS or the Si114x­M01-PS EVB's.

Following the search for a ribbon cable device, the demo will check the stored value of PB0 to enable or disable the
USB debug mode accordingly and display an USB On or USB Off message for 1 second. Refer to “4. USB Debug
Mode” for details on USB debug mode. Lastly, the demo will display version information then start the demo in
Heart Rate Monitor mode.

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Figure 5. Biometric-EXP Demo Startup Sequence

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Figure 6. Biometric-EXP Demo Modes

*Note: SpO2 Monitor mode is not available when using a HRM-GGG-PS, Si1143-M01-PS or Si1147-M01-PS.

3.2. Heart Rate Monitor Mode

When heart rate monitor demo is idle, the LCD will show the word “Pulse” followed by a message instructing the
user to place his/her finger on the optical sensor. In idle mode, the sensor is not continuously sampling. Rather, it
executes one sample ever y two seconds by performing a forced measurement . That sample is then analyze d to
determine if there is skin contact with the sensor. Only when the application detects skin contact does it begin
sampling continuously and running the HRM algorithm. It will remain in run mode (continuous sampling) until skin
contact is removed for greater than two seconds. This approach significantly reduces power usage when idle.

When the application is acquiring the heart rate, it will display the word “Wait” on the LCD. It typically takes five to
seven seconds to acquire a valid heart rate. Once a valid heart rate is measured, the display will show the heart
rate. If the heart rate is not displayed within seven seconds, it is likely that the algorithm cannot get a valid pulse
rate. When this occurs, the user should remove his/her finger and try it again adjusting the position of the finger
and the finger pressure as needed.

Proper finger position in relation to the sensor and LEDs as well as proper finger pressure is essential for accurate
measurements. The finger should fully cover both LEDs and the sensor. Proper finger position is illustrated in
Figure 7.

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Figure 7. Proper Finger Placement

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3.3. SpO2 Monitor Mode

When SpO2 mode is active, the LCD will show “SpO2” followed by a message instructing the user to place his/her
finger on the optical sensor. Beyond that, SpO2 monitor mode mirrors the operation of the Heart Rate Monitor
mode as described in “3.2. Heart Rate Monitor Mode” . Please note that SpO2 mode is not available when using a
HRM-GGG-PS, Si1143-M01-PS, or Si1147-M01-PS device via the 6-pin ribbon cable. Even more so than HRM,
proper finger position and pressure is important to achieve a good SpO2 measurement. Refer to Figure 7 for an
illustration of proper finger position.

3.4. Ultraviolet Sensor Mode

When the UV sensor mode is active, the LCD will show “UV” followed by the measured UV index. In this mode, the
UV reading is updated every two seconds.

3.5. Temperature Sensor Mode

In the temperature sensor modes, the LCD will show the temperature in Fahrenheit or Celcius as indicated by an
“F” or a “C” following the reading. In this mode the temperature reading is updated every two seconds.

3.6. Relative Humidity Sensor Mode

In the relative humidity sensor mode, the LCD will show “RH” followed by the relative humidity reading. In this
modem, the relative humidity reading is updated every two seconds.

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