Laird BT710 Sentrius Digital Contact Tracing Sensor User Guide

Laird BT710 Sentrius Digital Contact Tracing Sensor

ABOUT THIS GUIDE

This document provides a comprehensive guide on how to configure the Sentrius™ BT710 Contact Tracer functionality, including Bluetooth parameters, alert parameters, and general use for proximity sensing applications.

INTRODUCTION

Product Overview

The Sentrius™ BT710 Contact Tracer or “tag” is a battery-powered, Bluetooth v5 integrated sensing and contact tracing platform enabling tag-to-tag proximity sensing and logging along with tag-to-gateway communication for log upload. It contains several local alarm peripherals including four bright red LEDs, a bi- color status LED, an audible speaker, and a vibration motor (on wrist-worn models). For proximity sensing applications where local alarm indication is desired, the BT710 offers several user-configurable options to suit the use case. The BT710 is powered by Laird Connectivity’s field-proven BL653 BLE module that integrates Nordic Semiconductor’s nRF52833 SoC silicon.

1. Clasp
2. Status LED
3. Speaker
4. Alarm LEDs
5. Pushbutton

Note: Laird Connectivity has a comprehensive staff of design services engineers available to help customize the tracer. Please contact your local Laird Connectivity sales representative for more details.

Specifications

See the BT710 product brief for detailed specifications. It’s available from the BT710 series product page or from the following link: https://www.lairdconnect.com/documentation/product-brief-bt7x0-contact- tracer

DEVICE OPERATION

Activating the Tracer

The Sentrius™ BT710 is shipped with the battery installed and operating in a low-power state called Shipment Mode. When it arrives from the factory, the tracer is in shipment mode. To wake the device, press and hold the pushbutton for five seconds until the alarm LEDs turn on and a speaker tone is emitted along with the status LED lighting green and a brief vibration for devices equipped with that feature (startup sequence). This puts the tracer into Active Mode. The tracer blinks the status LED yellow waiting for its internal clock to be set, either by the BT710 mobile app or a nearby gateway. If a gateway is not available, connect the mobile app to automatically set the internal clock. Once in active mode with its clock set, the BT710 scans for compatible nearby tracers and transmits BLE advertisements for other tracers to sense. In active mode, the BT710 tracer can be configured using the associated Laird Connectivity BT710 mobile application. The default configuration sets the tracer to periodically scan for and log other tracers. Additional parameters include BLE advertising interval, RSSI sensing/proximity thresholds, proximity alarm timers, and alarm indicator styles.
There are two low-power modes: Non-Active and Power-Save. The tracer automatically enters these modes based on motion detection to extend battery life. User configurable parameters control timing for this feature. Separate BLE scanning parameters can be set for each operating mode to scan less frequently in Non-Active mode and Power-Save mode. The timeouts for entry into the low-power modes are also adjustable on the settings tab of the app .

Battery Check

Press and hold the pushbutton for three seconds to perform a battery check. The BT710 lights up a number of its red alarm LEDs to indicate the approximate voltage level of the battery.

• 4 LEDs with 75-100% battery life remaining
• 3 LEDs with 50-75% battery life remaining
• 2 LEDs on 25-50% battery life remaining
• 1 LED on: 0-25% battery life remaining

When the BT710 senses a battery below the low battery threshold parameter, it blinks the status LED quickly three times red at each scan interval. A small beep sequence is also emitted occasionally as a reminder to change the battery.

Factory Reset

If the button is held for more than 10 seconds, the status LED begins to rapidly blink yellow. Releasing the button performs a factory reset. A factory reset erases all logs and resets all parameters to defaults. The BT710 goes through a reset cycle when finished and emits the startup sequence LED pattern and beeps, followed by entry into active mode.

Replacing Batteries

The battery is a 3-volt lithium of CR2477 type.

Note: The battery door cover is underneath the clasp on the backside of the contact tracer. A coin may be used to aid in removal.

Active Mode Operation

When in Active mode, the tracer sequences through a series of BLE operations continuously including Scan, Advertise, and Connected. The Scan Interval parameter determines how much time passes between scan events, at which point the tracer awakes from sleep and performs a BLE scan (discovery of other tracers) for a number of seconds defined by the Scan Duration parameter. At each scanning interval, the status LED blinks to indicate the tag is scanning (see the LED Patterns section for details on LED blink patterns). When not connected, the tracer advertises (transmits) data for other tracers to receive when scanning. The rate of transmit events when performing the Advertise operation is determined by the Ad Interval parameter. The advertisement data contains identifiers to help filter out non-tracer devices, including device ID, TX power, and other status information. Flags in the advertisement indicate to gateway devices when a tracer has log data ready for download.

LED Blink Patterns

The tracer hardware uses a red/green status LED to indicate operating behavior to the user. The following table (Table 1) describes the LED patterns used to indicate status.
Table 1: Status LED Blink Patterns

Alarm Ranges

The tracer is equipped to trigger alarms at one of 3 distances from other tracers. These ranges are referred to as Range A, Range B, and Range C. Each range has its own configurable RSSI threshold, providing flexibility to trigger different alarm indicators depending on the distance from remote tracers. Using the BT710 mobile app interface, tap and drag the letter corresponding to the range to adjust, then fill in the corresponding fields below to set up the alarm configuration. Alarm 1 and Alarm 2 options allow setting different alarm indicators based on the amount of time a remote tracer has been within the specified RSSI range. The ranges are limited to be at least 4dBm apart from each other. The minimum range is -30 dBm (only Range A can be set to this value, due to the 4dBm range threshold difference). The maximum alarm range is -95 (only Range C can be set to this value, due to the 4dBm range threshold difference).

Alarm Styles

Several indicator styles are available providing control over how alarm LEDs, audible tones, and vibration motor feedback are activated when an alarm is triggered. These styles are configurable using the Alarms tab of the BT710 mobile application. When configuring the alarm style, the BT710 mobile application will trigger the new alarm style on the BT710 tracer to show the new alarm style (note, “Save Changes” must still be pressed in order to apply the new alarm style). Alarms are defined both by the duration of proximity (Alarm 1 vs. Alarm 2) and by the signal strength (RSSI) of each remote tag. Indicator styles may be selected independently for Alarm 1 and Alarm 2 conditions. The following table (Table 2) describes the styles available for each alarm indicator.
Table 2: Alarm indicator styles

Vibe Indicator                             Off                    No vibration will be triggered by the vibration motor Style 1     One long vibration

Style 2                 Two vibrations

Style 3                 Several short-pulsed vibrations

Style 4                 One long ripple vibration

Alarm Intensity| Low                   Lowers intensity of speaker and vibration indicators
---|---
High                  Normal intensity of speaker and vibration indicators

Care and Maintenance

The tracer can be cleaned with a mild, non-abrasive detergent. The tracer is not IP-rated/waterproof, so do not immerse it in water or cleaning fluids. The tracer does not require any calibration.

CONTACT TRACER ARCHITECTURE

The Sentrius™ BT710 advertises an identifying beacon used by other nearby BT710 contact tracers and gateways to log proximity to the tracer. This advertisement includes information such as a user-configurable device identifier, a hardware identifier, and the current status of the Bluetooth contact tracer. You can configure a tracer using a Bluetooth connection and the Laird Connectivity Sentrius™ BT710 mobile application.

Bluetooth Advertisements

The following tables describe the data available in the advertisements for the BT710 tracer. Once a tracer is configured, it is possible for a mobile app or gateway to connect to the BT710 device for the configuration of parameters and/or data log download. The BT710 device can be configured to transmit with an output power of -20 to +8 dBm. 4.1.1 IM PHY

Table 3: 1M PHY

IM PHY Scan Response

Ad Record Types

Bluetooth Advertisement Field Details
Company 1D Field
This is always Ox0077, the Company 1ID for Laird Connectivity.
Protocol ID Field
This is always 0xFF81, the protocol for the BT510-CT and BT710 tracers.
Network ID Field
This is user programmable via the NETWORK_ID parameter. Defaults to OxFFFF.
Flags Field

Table 6: Flags field

__

Bit 0 (0x0001)                  HAS_EPOCH_TIME

| 0| Clock time not set
1| Clock time set
__

Bit 1 (0x0002)                    HAS_LOG_DATA

| 0| Data log not ready
1| Data log ready for download
__

Bit 2 (0x0004)                         RESERVED

| 0| Reserved
1| Motion Reserved
__

Bit 3 (0x0008)                     LOW_BATTERY

| 0| Battery good
1| Battery low
__

Bit 4 (0x0010)                    DATALOG_FULL

| 0| Datalog is not full
1| Datalog is full

Device ID Field

• This is the device ID currently advertised by the BT710.
• Ad Record Type and Ad Record Data Fields
• The Ad Record Type byte indicates the format of the remaining bytes to follow in the advertisement data (the Ad Record Data).
• The list of defined Ad Record Types and corresponding data format is displayed in the following table (Table 7).
• Table 7: 0x10 – Ad Tracking Record

Field Name Size (Bytes) Data Type Description

0x10 – BL654 DVK

0x20 – BL653 DVK

0x30 – BT710

0x40 – MG100

0x50 – IG60

Battery Voltage| 1| uint8| Battery voltage divided by 16 (in millivolts)
Firmware Version| 1| uint8| 4 MSB bits: Major version, 4 LSB bits: Minor version
Field Name| Size (Bytes)| Data Type| Description
---|---|---|---
Firmware Build| 1| uint8| Build version

Tracer Configuration

The tracer has several parameters that can be used to tailor it for each use case. The table below lists the common parameters that can be adjusted by the user based on the use case to the tracer is being applied to. These parameters can be updated using the BT710 mobile application.

General Settings
Tx Power                                                    +8 dBm Transmit power of BLE radio (-20dBm to +8dBm)
Active Scan Interval                                   10 sec Seconds between scan/discovery events (Active Mode)

Active Scan Duration| 2 sec| How long to scan for/discover nearby tracers (Active Mode)
---|---|---
Active Ad Interval| 250 ms| Milliseconds between advertisement TX events (Active Mode)
Active Motion Timeout| 300000 ms| Milliseconds of no motion to trigger “Non- Active Mode” from “Active Mode”
Non-Active Scan Interval| 120 sec| Seconds between scan/discovery events (Non- Active Mode)
Non-Active Scan Duration| 2 sec| How long to scan for/discover nearby tracers (Non-Active Mode)
Non-Active Ad Interval                              500 ms Milliseconds between advertisement TX events (Non-Active Mode)

Non-Active Motion Detect                         500 ms Milliseconds of motion to wake from “Non-Active Mode”

Power Save Scan Duration                         1 sec               How long to scan for/discover nearby tracers (Power-Save Mode)

Power| Save| Motion| Detect| 500| ms| Milliseconds of motion to wake from “Power-Save Mode”
---|---|---|---|---|---|---
Logging
Profile| 0| User-assignable value for categorizing tracer types
How often data log is available for download (if present)? Datalogging and data

Log Interval: 2 min

the collection is disabled if this value is set to 0.

Discovery Duration: 300 sec: Time a tracer must be observed before logging into storage

Logging Threshold                                 – 99 dBm            Tracers with RSSI value less than this threshold will be ignored

Alarms
RANGE A
Range A Alarm 1 RSSI Threshold           -52 dBm             Trigger alarm if a tracer is detected with signal greater than this value

Range A Alarm 1 Speaker

Style 4              Selects style for the speaker indicator when alarm 1 is triggered

Indicator

Range A Alarm Intensity                             High               Normal intensity speaker/vibe indicator level

Range A Alarm 2 Indicator Styles             Style 4              Selects style for the vibration motor indicator when alarm 2 is triggered

RANGE B

Range B Alarm 1 RSSI Threshold           -60 dBm             Trigger alarm if a tracer is detected with signal greater than this value

Range B Alarm 1 Speaker

Off                 Selects style for the speaker indicator when alarm 1 is triggered

Indicator

Range B Alarm Intensity                             High               Normal intensity speaker/vibe indicator level

Range B Alarm 2 Red LED

Style 3              Selects style for the red LED indicators when alarm 2 is triggered

Indicator

Range B Alarm 2 Indicator Styles                Off                 Selects style for the vibration motor indicator when alarm 2 is triggered

RANGE C

Range A Alarm 1 RSSI Threshold           -71 dBm             Trigger alarm if a tracer is detected with signal greater than this value

Range C Alarm 1 Speaker

Off                 Selects style for the speaker indicator when alarm 1 is triggered

Indicator

Range C Alarm Intensity                             High               Normal intensity speaker/vibe indicator level

Range C Alarm 2 Red LED

Off                 Selects style for the red LED indicators when alarm 2 is triggered

Indicator

Range C Alarm 2 Indicator Styles               Off                 Selects style for the vibration motor indicator when alarm 2 is triggered

Parameter Selection Considerations

The parameters provide flexibility in the configuration of timing and operation of the tracer for different use cases. For example, a fixed location asset tracker may be suited to scanning less often than a mobile tracer. The configuration parameters affect how often the tracer operates in each mode and therefore have a direct impact on the responsiveness/latency of the log entries and battery life of the device. These parameters must be considered carefully for the log data to serve the purpose of a specific tracking application. The highest power usage occurs when the tracer is scanning/discovering other tracers. In this mode, the device is both transmitting its BLE advertisements and has the radio receiver turned on to discover nearby tracers for logging. The defaults target use cases where batteries are changed about once a month. If more time is necessary, the scan interval can be increased (scan less frequently), the scan duration can be decreased (scan for a shorter time period), or the advertising interval can be adjusted to keep the radio in sleep mode more often, thus extending useful battery life. TX power is also a consideration as higher power settings reduce battery life.

Note: Scan interval, scan duration, and ad interval can be set separately for Active mode, Non-Active mode, and Power-Save mode. By increasing the scan interval and reducing the scan duration and ad interval during Non-Active mode and Power-Save mode, the tracer can conserve battery life when motion is not detected. For best power savings, set the Power-Save mode scan duration to a value of zero to keep from scanning altogether when the tracer has been idle (no motion) for an extended period.

Firmware Updates

The BT710 Contact Tracer supports over-the-air (OTA) firmware updates when paired with an appropriate Laird Connectivity mobile application or supporting gateway product. The process uses a standard DFU mechanism that can be incorporated into customer apps/products for compatibility. For more details regarding integration into your own tracking solution, please contact the Laird Connectivity sales team member for your region.

Proximity Alarms

The tracer implements programmable alarms that can be used to trigger local audio, visual, and haptic indicators when a remote tracer is detected within an RSSI range for a configured amount of time. Each alarm has a parameter indicating the number of seconds a remote tracer must be detected before triggering the alarm indicators and a corresponding RSSI threshold.  For each scanning interval, the tracer determines which tracers are within proximity and meet the configured RSSI threshold to begin logging. A counter increases each time that same tracer is observed in a scan. Once [the number of scan intervals a tracer is detected] x [Scan Interval parameter] is equal or greater than the configured alarm timer, the alarm indicators are triggered for each subsequent scan that tracer is detected until the configured contact period expires or the remote tracer moves out of proximity.  The following diagram (Figure 4) shows the proximity alarm timeline given default parameter values.

As a tracer detects other remote tracers (“remotes”) in a BLE scan, each remote enters into a RAM-based discovery database in order to track the number of scan intervals each is seen for alarming purposes. Each remote has its own timeline from the perspective of the sensing tracer. Each time a remote is detected in a BLE scan, a count of seconds is added to that remote’s total detection time in the database. This number of seconds is equal to the Active Scan Interval parameter. If a remote is not detected in a scan, the total detection time in its database entry is not incremented for that scan interval. For example, with default parameters, each scan interval a remote is detected adds 10 seconds to its total detection time in the database. After any remote is detected in enough scans such that the total detection time crosses a configured alarm threshold, the configured alarm indicators are triggered to alert the user. The alarm continues to trigger each scan interval until no remotes having a total detection time longer than the alarm time setting are within range. Once “Contact Period” seconds passes since the first time a remote is detected, the total detection time for that remote is reset to zero in the database, starting a new proximity alarm timeline once it is detected in a future scan. Note that though alarms can be configured for different ranges (A, B and C), the closest proximity alarm takes priority, meaning if conditions for a range A alarm are met, the range B and range C alarms will not be triggered. Likewise, if a range B alarm condition is met, alarm C will not trigger.

Data Logging

The BT710 is designed to log data from other compatible tracer devices it observes during its BLE scan operations. The logging functionality can be disabled through the Log Interval parameter (set Log Interval to 0). The following diagram (Figure 5) shows the data logging timeline and how various parameters affect each logging phase.

As a tracer detects remote tracers (“remotes”) in each BLE scan, the discovery database is updated and the remote steps through three phases of logging throughout a single Contact Period.

• Discovery Phase – Remote tracers are tracked in a RAM-only discovery database for each scan they are detected. Once the total detection time is greater than the configured Discovery Duration, the records for the remote are committed to a Flash-based log and the remote enters Tracking Phase. If a remote is only detected with fewer scan intervals than the configured Discovery Duration within a given Contact Period, the remote is not logged to Flash. This is useful for situations where tracers are in proximity for very brief periods of time and do not warrant storage to the Flash-based log. Discovery Phase stores a maximum of 10 records per remote before automatically moving into Tracking Phase.
• Tracking Phase – Remote tracers in the Tracking Phase get an additional record in the Flash-based log for every scan interval they are detected, up to the maximum records that can be recorded for the duration of the Tracking Phase (set with the Tracking Duration parameter).
• Untracked Phase – If a remote tracer has been detected for the entirety of the Tracking Phase, no more records are made for that remote until the Contact Period expires or that entry is collected by a gateway. This limits the maximum number of Flash log records that are used by a single remote per Contact Period, allowing the remaining Flash space to be used for the detection and logging of other remote devices during the Contact Period.

Data Log Entries

The number of unique remote tracers that can be logged is a function of the Scan Interval and Tracking Duration parameters. For example, with Scan Interval of 30 seconds, Tracking Duration of 15 minutes and Contact Period of 24 hours, up to 50 remote tracers can be logged for 1 week before the log is full. Once the log is full, the oldest entries are overwritten with new entries in first-in-first-out order. The following data is logged at each scan interval from a remote tracer’s advertisement:

Figure 6 – Data logged for each remote tracer detected in BLE scans

MOBILE APPLICATION

Overview

The Sentrius™ BT710 mobile application allows a user to configure tracer parameters and update the firmware.

1. From the applicable app store (Apple or Android) search for and install the Sentrius™ BT710 mobile application on your mobile device.
2. To connect to the BT710, make sure it is in Active mode.
3. Tap FIND BT7 DEVICE to discover the tracer(s) within range of the mobile device.
4. Select the tracer to connect. Tracer names start with BT710 and end with the last four digits of the BLE ID as printed on the device QR code. Once connected, the app displays the current parameter values configured for the tracer. Parameters are grouped using tabs near the bottom of the page.

REGULATORY

Note: For complete regulatory information, refer to the BT710 Regulatory Information document which is also available from the BT710 product page.

The BT710 holds current certifications in the following countries:

Canada (ISED) 3147A-BT710

ORDERING INFORMATION

450-00122-K1| SentriusTM BT710 Bluetooth Contact Tracer, with Clip, Single| Single (1)
---|---|---
450-00134-K1| SentriusTM BT710 Bluetooth Contact Tracer, with Vibration, with Wrist Strap, Single| Single (1)
450-00122B| SentriusTM BT710 Bluetooth Contact Tracer, with Clip, BULK| Bulk (100)
450-00059B| SentriusTM BT710 Bluetooth Contact Tracer, BULK| Bulk (100)
450-00134B-K1| SentriusTM BT710 Bluetooth Contact Tracer, with Vibration, with Wrist Strap, BULK| Bulk (100)

LABEL INFO

• The QR Code contains the part number, hardware revision, date code, and BLE ID (ALL Caps)
• Example Readout: 450-00122;1;0920542; CB09AE5B8D7F

FREQUENTLY ASKED QUESTIONS

Please refer to the support FAQs online which can be found here:- https://www.lairdconnect.com/support/faqs

ADDITIONAL ASsISTANCE

• Please contact your local sales representative or our support team for further assistance
• Laird Connectivity
• Support Centre:https://www.lairdconnect.com/resources/support
• Email: Wireless.support@lairdconnect.com
• Phone: Americas: +1-800-492-2320
• Europe: +44-1628-858-940
• Hong Kong: +852 2923 0610
• Web:https://www.lairdconnect.com/iot-devices/iot-sensors/sentrius-bt7 10-contact-tracer-multi-sensor
• © Copyright 2020 Laird Connectivity. All Rights Reserved. Any information furnished by Laird Connectivity and its agents is believed to be accurate and reliable. All specifications are subject to change without notice. Responsibility for the use and application of Laird Connectivity materials or products rests with the end user since Laird Connectivity and its agents cannot be aware of all potential uses. Laird Connectivity makes no warranties as to non-infringement nor as to the fitness, merchantability, or sustainability of any Laird Connectivity materials or products for any specific or general uses. Laird Connectivity or any of its affiliates or agents shall not be liable for incidental or consequential damages of any kind. All Laird Connectivity products are sold pursuant to the Laird Connectivity Terms and Conditions of Sale in effect from time to time, a copy of which will be furnished upon request. Other marks may be the property of third parties. Nothing herein provides a license under any Laird Connectivity or any third party intellectual property right.
• https://www.lairdconnect.com/bt7x0-series
• 18 © Copyright 2021 Laird Connectivity, Inc. All Rights Reserved
• Americas: +1-800-492-2320
• Europe: +44-1628-858-940
• Hong Kong: +852 2923 0610

Documents / Resources

| Laird BT710 Sentrius Digital Contact Tracing Sensor [pdf] User Guide
BT710, Sentrius, Digital Contact Tracing Sensor, BT710 Sentrius Digital Contact Tracing Sensor, Tracing Sensor
---|---

References

• 📧wireless.support@lairdconnect.com
• Sentrius™ BT710 & BT720 Digital Contact Tracing Sensor
• Product Brief - BT7x0 Contact Tracer | Laird Connectivity
• Regulatory Information - BT710 | Laird Connectivity
• Sentrius™ BT710 & BT720 Digital Contact Tracing Sensor
• Sentrius™ BT710 & BT720 Digital Contact Tracing Sensor
• Support
• Laird Connectivity FAQ's

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