nRF51: Sleeping a certain time

[mr91]

Hello,

my program should do the following:

• Collect sensor data
• Initialize SD and start advertising
• After a timeout or after a successful data connection it should sleep for half an hour.
• When waking up, it should start from the beginning.

Question: How can I implement this long sleep period in an efficient (most powersaving) way?

Thank you!

[Roger Clark]

Why not just use a timer ?

[Jørgen Holmefjord]

Hi,

You should use a timer to set a periodical wakeup from sleep to collect and send sensor data. I would recommend that you take a look at the Application Timer Tutorial. The application timer module use RTC instead of timers, which is more power efficient. You can also take a look at this nRF52 ADC example, where a RTC is setup for periodical capture of battery voltage.

Notice that you can only use system on sleep mode, when using timers. System off sleep mode will disable all clock sources.

An alterantive, which might be more power efficient, is to add an external ULP timer. You can then put the nRF device in system off mode, lowering the current consumption compared to system on mode, and configure the device to wake on GPIO/GPIOTE. You can find some exampes of the different sleep modes on GitHub.

Best regards,

Jørgen