nRF Connect SDK ST BLE Sensor example

[psyspy]

Hello! I tested the ST BLE Sensor sample on my nrf52840 DK. I have a few questions about the source code:

1. Looking at recv(), connected() and disconnected() functions, seems like they are event driven and asynchronous. Is this correct?

2. Is it single threaded?

3. What happens (which mode) when the MCU is waiting for events? Either during advertising (no devices connect to it yet) or waiting for recv or button press. I saw System On idle mode, System Off sleep mode in another thread. Not sure if there are other modes. 

4. Does the rtos automatically handle putting the MCU in idle/sleep mode or do I have to do it (call some sleep function) when it's waiting for events?

Thanks! 

[Vidar Berg]

Hello,

1. Yes, the callbacks are asynchronous.

2. All BLE applications are multi-threaded.

3. The OS will automatically execute the idle thread (https://developer.nordicsemi.com/nRF_Connect_SDK/doc/1.9.1/zephyr/reference/kernel/threads/system_threads.html) when there is no work to do and make the device enter System ON mode. System OFF mode is the other deep sleep mode available on the device. In this mode the chip is basically powered down. Wakeup from system OFF triggers a system reset.

4. Yes, it will automatically enter the idle thread. For instance, when your app is waiting for a semaphore or call k_sleep() from one of your threads.

Best regards,

Vidar