How can I wake up BLE device from power system off mode without buttons

[Adavid]

Dear all: recently, I follow heart rate profile to write custom BLE profile,but I also went to a number of issues. how to wake up the device when entered power system off mode via software . By the way . why the connnection will be automatically disconnected ?

Best Regards

[Sébastien Despont]

Every BLE examples in the SDK 4.2 have the behaviour you expect. The device switch in system_off mode after the adertising timeout.

Therefore, you cannot be disconnected until a voluntary disconnection from the connected device.

Just before switch off, a GPIO pin is defined to be able to wake up the chip. By wake up. I mean do a reset : the main function will be executed.

Have a look in the BLE examples for more information.

[Adavid]

Thanks a lot for your help. If I conntinue to connect seems not meet the bluetooth low power .

[Ole Morten]

It's a little unclear to me what you actually want to achive, but as Sébastien correctly points out, most SDK examples uses a GPIO to wake up from system off.

However, if you want to wake up without a GPIO (or reset), you can not use the system off mode, and instead you should rely on using the regular WFI mode, by using for example sd_app_event_wait(). This will enable you to wake up on for example RTC events or similar.

[Ole Morten]

It is quite hard to understand exactly what you're trying to ask, but I've posted a separate answer. If this doesn't answer your question, it would have been useful if you could elaborate a bit on what you need to know and what you try to achieve.