In AP i can set the beacon_interval, but i cannot set the DTIM directly.
And i see,after sniffing packets on air, that my AP decides the appropriate DTIM by its own.
Not good, because it controls the wake up from from light sleep of a connected client to let the client respond to the beacon.
And due to the unknown processes of the proprietary stack my light sleep entering is very unstable if i need to repeat it.
I need to let my application in idle state for a lot of milliseconds after some spi ping pongs and subsequent tcp tx/rx to be sure espressif enters the light sleep in a predictable manner ( no timers disturbing ).
The picture below display on an espressif used as client:
- current consumption ( yellow )
- spi ping pong ( violet and blue ) , when it ends it means that even tcp tx/rx is completed.
Beacon interval is set to 200 ms, and i can see it with Wireshark.
DTIM period is 2, i.e client has to wake up every 2 beacons, check the single spike that occurs every 400ms.
The module is inside a board but i think i can relate the other yellow spikes, when esp is on, to the activities of the AP dealing with other beacon/probes requests..wierd reflection on the client isn't it?
Note the extra time time where espressif is on before entering light sleep, i need to allow this delay eitherway no light sleep at all.