AN92584 Datasheet, PDF (38/42 Pages) Ramtron International Corporation – Designing for Low Power and Estimating Battery Life for BLE Applications

Designing for Low Power and Estimating Battery Life for BLE Applications
7 Appendix B: Connection State Current Profile
A connection is set up between two BLE devices: one acting as a Central (referred to as the Master at the Link Layer)
and the other as a Peripheral (referred to as a Slave at the Link Layer) for exchanging application data. The Central
and Peripheral devices exchange data by transmitting and receiving packets at connection events. The Central
device starts the connection event by transmitting first. The devices then alternate transmitting and receiving data
until they stop the exchange and close the connection event. The starts of connection events are spaced with a
periodic interval of connInterval. The connInterval is a multiple of 1.25 ms in the range of 7.5 ms to 4 s, per the BLE
specification.
In addition to the connection interval (connInterval), the connSlaveLatency parameter defines the number of
consecutive connection events that the Peripheral device is not required to listen to the Central device. These
parameters together determine the timing for connections. A BLE connection event with zero slave latency is
illustrated in Figure 22.
Figure 22. Connection Event and Interval
M to S
S to M
M to S
S to M
T_IFS
T_IFS
T_IFS
Connection
Event
connInterval
Connection
Event
connInterval
Connection
Event
Legend
M : Master
S : Slave
7.1.1
Current Profile
A connection state current profile for a PSoC 4/PRoC BLE Peripheral device considering this approach is shown in
Figure 23. The figure illustrates the power modes used, along with the BLESS internal state transitions and relative
current levels.
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Document No. 001-92584 Rev. *A
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