Texas Instruments CC2540DK-MINI Application Guide

TI CC2540 Bluetooth low energy Sample Applications Guide v1.4.1 SWRU297 Version 1.4.1
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13 SensorTag
The SensorTag is a BLE peripheral slave device which runs on the CC2541 SensorTag hardware
platform. The Sensor Tag includes five peripheral sensors with a complete software solution for
sensor drivers interfaced to a GATT server running on TI BLE stack. The GATT server contains a
primary service for each sensor for configuration and data collection.
13.1 Operation
On startup, the SensorTag is advertising with a 100ms interval. The connection is established by
a Central Device and the sensors can then be configured to provide measurement data. The
Central Device could be any BLE compliant device and the main focus is on BLE compliant
mobile phones, running either Andriod or iOS. The central device should be able to
 Scan and discover the Sensor Tag. (Scan response contain name “SensorTag”)
 Establish connection based on user defined Connection Parameters
 Perform Service Discovery – Discover Characteristic by UUID
 Operate as a GATT Client - Write to and read from Characteristic Value
The Central Device shall initiate the connection and thereby become the Master.
To obtain the data, the corresponding sensor must first be activated, which is done via a
Characteristic Value write to appropriate service.
The most power efficient way to obtain measurements for a sensor is to
 Enable notification
 Enable Sensor
 When notification with data is obtained at the Master side, disable the sensor (notification
still on though)
Alternative do not use notifications at all, then simply
 Enable sensor
 Read data and verify
 Disable sensor
For the latter alternative please keep in mind that sensor take different amount of time to perform
measurement. Depending on the connection interval (~10 – 4000 ms) set by the Central Device,
the time for achieving measurement data can vary. The individual sensors require varying delays
to complete measurements. Recommended setting is 100ms but for fast accelerometer and
Magnetometer data updates, a lower is necessary. Notifications can be stopped and the sensors
turned on/off
13.2 Sensors
The SensorTag has support for the following sensors:
 IR Temperature, both object and ambient temperature
 Accelerometer, 3 axis
 Humidity, both relative humidity and temperature
 Magnetometer, 3 axis
 Barometer, both pressure and temperature
 Gyroscope, 3 axis
13.3 Buttons
 Side Button: When not connected, this button is used to toggle advertising on and off.
When in a connection, this terminates the current connection. Pressing this button for
more than 3 seconds resets the system.

Texas Instruments CC2540DK-MINI Specifications

General

Brand	Texas Instruments
Model	CC2540DK-MINI
Category	Microcontrollers
Language	English