Functional description
KW40 Heart Rate Monitor Using Bluetooth Low Energy, User's Guide, Rev. 0, 10/2015
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Freescale Semiconductor, Inc.
4. Functional description
This chapter describes the device behavior across all its functional phases. It comprises all the required
information to fully understand the application’s functionality.
4.1. Battery Retention State
The battery retention state consists of turning off all the board indicators and program the KW40Z SoC
to be in a low power state for battery saving.
The device can only exit from this state by connecting the battery charger or by entering the device in
Advertising State (see the next section,
).
The device enters in this state if a connection is not established during the advertising state or by
pressing the application button either when the device is advertising or connected.
4.2. Advertising State
When the device is in advertising state, presence reports are transmitted over the air so the BLE devices
nearby can be aware of the device’s availability for connection.
To enter the advertising phase, the device must be in Battery Retention State (see section
) and the
application button must be pressed. The green LED will start blinking to indicate that the device is in the
Advertising State (see
Figure 4. Device advertising
The device will advertise for 30 seconds. If a connection is not detected during that time interval, the
device enters the battery retention state.
