[request] Replace polling by event in Matter examples

[rei-vilo]

Summary

In many examples, delay before two consecutive data acquisition is performed by polling.

https://github.com/SiliconLabs/arduino/blob/65a739a859fa8b98e755f23f2b9c8010d25ca1e2/libraries/Matter/examples/matter_sensor_multiple/matter_sensor_multiple.ino#L61-L67

This might not be especially low-power.

How to use instead an event raised by a timer? As SiLabs core for Arduino seems to rely on FreeRTOS, the RTOS elements should be already available.

Thank you!

[silabs-bozont]

Hello @rei-vilo,

Yes, the examples use polling - so they're might not be that power efficient. We'll look into introducing event callbacks to the library so you can block your user task and wait for Matter events to happen - it's a good idea.

[silabs-bozont]

Hello @rei-vilo,

I just realized what you need here is to replace the busy-looping with a simple delay() - that'll block the user task for the provided amount of time allowing the device to enter a low-power mode and also run the radio stack if necessary. We'll also introduce support for ArduinoLowPower to allow more control.

What I was thinking about is the ability to register a callback for your devices which is called when some property changes. This would allow you to block your user task and go low power until something changes - then only react to it once without constantly polling for changes. This will be very useful, so it'll be definitely coming.

[rei-vilo]

Thank you for the suggestion.

Actually, a delay() fits perfectly if there is only one single task.

As the weather sensor can raise an interrupt, I am considering using events. This is what I did for the Low Power Home Network Weather Monitoring project based on sub-1GHz and TI-RTOS: idle mode required as little as 0.0267 mW.