Phone Alert Status Profile

The Peripheral shall enter a GAP Limited Discoverable Mode when establishing an initial connection. The T_GAP (lim_adv_timeout) used during GAP Limited Discoverable Mode may be larger than the value specified in the Section 16, Appendix A in the GAP specification [1], but the value shall be less than or equal to 180 seconds.

This procedure is used for device discovery and connection establishment when the Peripheral connects to a Central to which it is not bonded. This procedure is initiated by user interaction (like activating the device by battery insertion).

It is recommended that the Peripheral advertise using the parameters in Table 5.1. The interval values in the first row are designed to attempt fast connection during the first 30 seconds; however, if a connection is not established within that time, the interval values in the second row are designed to reduce power consumption for devices that continue to advertise.

The advertising interval and time to perform advertising should be configured with consideration for user expectations of connection establishment time.

The Peripheral shall accept any valid values for connection interval and connection latency set by the Central until service discovery, bonding, and encryption setup is complete. Only after that should the Peripheral change to the preferred connection parameters that best suits the use case.

If a connection is not established within a time limit defined by the Peripheral, the Peripheral may exit the GAP connectable mode.

After bonding the Peripheral should write the Bluetooth address of the Central in the Peripheral controller’s white list and set the Peripheral controller’s advertising filter policy to ‘process scan and connection requests only from devices in the White List’.

This procedure is used after the Peripheral has bonded with the Central device using the connection procedure in Section 5.1.2 when the user initiates a connection.

A Peripheral shall enter the GAP Undirected Connectable Mode when commanded by the user to initiate a connection to a Central device.

The Peripheral should use the advertising filter policy configured when bonded using the connection procedure in Section 5.1.2.

The Peripheral should use the recommended advertising interval values shown in Table 5.1.

The advertising interval and time to perform advertising should be configured with consideration for user expectations of connection establishment time.

The Peripheral shall accept any valid values for connection interval and connection latency set by the Central until service discovery and encryption setup is complete. Only after that should the Peripheral change to the preferred connection parameters that best suits its use case.

If a connection is not established within a time limit defined by the Peripheral, the Peripheral may exit the GAP connectable mode.

When a connection is terminated due to link loss a Peripheral should attempt to reconnect to the Central by using the procedures described in 5.1.2 or 5.1.3.

The Central should use the GAP Limited Discovery Procedure to discover a Peripheral.

This procedure is used for connection establishment when the Central connects to a Peripheral to which it is not bonded. This procedure is normally initiated by user interaction.

A Central may use one of the following GAP connection establishment procedures based on its connectivity requirements:

A Central should use the recommended scan interval and scan window values shown in Table 5.2. For the first 30 seconds (or optionally continuously for mains powered devices), the Central should use the first scan window / scan interval pair to attempt fast connection. However, if a connection is not established within that time, the Central should switch to one of the other scan window / scan interval options as defined below to reduce power consumption.

* A scan interval of 60ms is recommended when the Central is supporting other operations to provide a 50% scan duty cycle versus 100% scan duty cycle.

Option 1 in the table above uses the same background scanning interval used in BR/EDR so the power consumption for LE will be similar to the power consumption used for background scanning on BR/EDR. Option 2 uses a larger background scanning interval (e.g. twice as long) than used in BR/EDR so the power consumption for LE will be less than the power consumption used for background scanning on BR/EDR. Connection times during background scanning will be longer with Option 2.

After bonding, the Central should write the Bluetooth address of the Peripheral in the Central controller’s white list and set the Central controller’s initiator filter policy to ‘process connectable advertisement packets’.

This procedure is used after the Central has bonded with the Peripheral using the connection procedure in Section 5.2.2 and the user initiates a connection.

A Central may use one of the following GAP connection establishment procedures based on its connectivity requirements:

The Central should use the recommended scan interval and scan window values shown in Table 5.2. For the first 30 seconds (or optionally continuously for mains powered devices), the Central should use the first scan window / scan interval pair to attempt fast connection. However, if a connection is not established within that time, the Central should switch to one of the other scan window / scan interval options as defined below to reduce power consumption.

The Central should use a scan window and scan interval suitable to its power and connection time requirements. Increasing the scan window increases the power consumption, but decreases the connection time.

The scan interval and scan window should be configured with consideration for user expectations of connection establishment time.

The Central shall start encryption after each connection creation to verify the status of the bond. If encryption fails upon connection establishment (i.e., The bond no longer exists), the Central must, after user interaction, re-bond, perform service discovery (unless the Central had previously determined that the Peripheral did not have the «Service Changed» characteristic) and reconfigure the Peripheral before using any of the services referenced by this profile in case the configuration was altered or lost.

When a connection is terminated due to link loss a Central should attempt to reconnect to the Peripheral using any of the GAP connection procedures and using procedures described in sections 5.2.2 or 5.2.3 .

To avoid very long service discovery and encryption setup times, the Central should use the connection intervals defined in Table 5.3 in the connection request.

At any time a key refresh or encryption setup is required, for example to perform key refresh, this should be preceded with a connection parameter update to the minimum and maximum connection interval values in Table 5.3 and a latency of zero. This fast connection interval should be maintained as long as low latency is required. After that, it should switch to the preferred connection parameters as decided by the Peripheral using the GAP Connection Parameter Update procedure.