Bluetooth External Radio Coexistence examples

3-Wire interface
- Timing parameters

3-Wire interface 

This section contains example timing diagrams for each supported Bluetooth® Low Energy Link Layer state. The diagrams describe the coexistence interface’s signal activity and the related radio activity.

Note

See Bluetooth External Radio Coexistence for the protocol details.

Timing parameters 

The 3-wire coexistence interface has the following timing parameters:

Extended timeslot example
Symbol	Value	Min	Max	Description
t_type	Configurable	2 μs		Time from activating BLE_REQUEST until the direction of the requested radio activity is indicated.
t_radio	Configurable	5 μs		Time from the expiration of t_type until the radio can assume that the request has been granted.
t_type + t_radio		7 μs	40 μs
t_{radio_off_delay}			10 μs non CODED PHYs 15 μs CODED PHYs	Maximum delay from the time BLE_GRANT is deactivated until the radio is turned off.
t_{max_BLE_GRANT_reactivation_delay}	100 μs			Maximum delay from the time BLE_GRANT is deactivated until it is reactivated.

During t_type, PTA samples the BLE_PRIORITY line to get the priority of the request. An active state indicates that the request has high priority. During t_radio, PTA samples the BLE_PRIORITY line to get the direction of the requested radio activity. The application can configure whether a reception is indicated by an active or inactive state. All timing diagrams assume that a reception is indicated by an active state.

Coexistence interface timing parameters

Connection event

When in a connected state, a request for radio activity to PTA consists of a single TX-RX pair. A connection event may consist of a multitude of such pairs.

An example of a connection event where the SoftDevice Controller is in a connected state as a slave is shown below. The depicted connection event consists of two TX-RX pairs. Within the request and when the BLE_REQUEST signal is active, the BLE_PRIORITY signal toggles t_radio prior to reception.

Advertising

When in the advertising state, a request for radio activity to PTA consists of the transmission of a single advertising indication. Any subsequent radio activity triggered by such a packet, for example receiving and responding to a scan request, is part of the same request. The transmission of a legacy scannable advertising indication in all three primary advertising channels is shown below.

The BLE_REQUEST signal is activated before the transmission of every advertising indication. After transmitting an advertising indication, the BLE_PRIORITY signal toggles for the potential reception of a scan request. After the transmission of the third advertising indication, the BLE_PRIORITY signal toggles first for the reception of the scan request and then again for the transmission of the scan response.

The figure below shows the transmission of an extended scannable advertising indication in all three primary advertising channels, along with the transmission of an auxiliary advertising indication on a secondary advertising channel. Compared to Legacy scannable advertising figure above, the BLE_REQUEST signal is deactivated after the transmission of the advertising indication in the primary advertising channels, because a scan request is expected only after the transmission of the auxiliary advertising indication.

Scanning

When in scanning/initiating state, a request for radio activity to PTA begins when the access address of an advertising packet has been received. Examples of this configuration are depicted in the following figures Legacy active scanning, request on access address match and Extended active scanning, request on access address match. The timing interval t_aa represents the time needed to perform the access address match.

Any subsequent radio activity triggered by the reception of an advertising indication, such as the transmission of a scan request and the reception of a scan response, is part of the same request.

Legacy active scanning, request on access address match

Extended active scanning, request on access address match

Request denial

PTA can deny a request at any time after the request has been considered granted. A denial is indicated by a deactivation of the BLE_GRANT signal.

An example of a connection event where the SoftDevice Controller is in a connected state as a slave is shown below. In the example, the request for the first TX-RX pair is denied during the request. There is no subsequent request for the following TX-RX pair. In general, when a request associated with a connected state is denied, the corresponding connection event is aborted.

The transmission of a legacy scannable advertising indication is shown below. The first request is denied during the transmission of the advertising indication. There is a subsequent request for the transmission of the advertising indication in the next advertising channel.

Request denied during legacy advertising