This section describes the processor availability and interrupt processing time for the SoftDevice when the advertiser (broadcaster) role is running.
When advertising, the pattern of SoftDevice processing activity for each advertising interval at interrupt priority level 0 is as follows:
SoftDevice processing activity in the different priority levels when advertising is outlined in Processor usage when advertising. The typical case is seen when advertising without using a whitelist and without receiving scan or connect requests. The max case can be seen when advertising with a full whitelist, using private addresses, receiving scan and connect requests while having a maximum number of connections and utilizing the Radio Timeslot API, Flash memory API, using PA/LNA, and Quality of Service (QoS) channel survey module at the same time.
Parameter | Description | Min | Typical | Max |
---|---|---|---|---|
tISR(0),RadioPrepare | Processing when preparing the radio for advertising | 32 μs | 50 μs | |
tISR(0),RadioStart | Processing when starting the advertising | 12 μs | 20 μs | |
tISR(0),RadioProcessing | Processing after sending/receiving a packet | 54 μs | 75 μs | |
tISR(0),PostProcessing | Processing at the end of an advertising event | 77 μs | 128 μs | |
tnISR(0) | Distance between interrupts during advertising | 40 μs | >170 μs | |
tISR(4) | Priority level 4 interrupt at the end of an advertising event | 28 μs |
From the table we can calculate a typical processing time for one advertisement event sending three advertisement packets to be:
tISR(0),RadioPrepare
+
tISR(0),RadioStart
+
2 *
tISR(0),RadioProcessing
+
tISR(0),PostProcessing
+
tISR(4)
=
257
μs
That means typically more than 99% of the processor time is available to the application when advertising with a 100 ms interval.