remote wake up

[karoun]

Hello,

I am integrating saadc example to ble_uart in order to receive analog input signals and send them via ble connection to android application. Low power consumption is an important consideration in this application. I am looking for a way that I could send a wake up call to the device via android application and then device start advertising and sending data(for example in blinky example there is this possibility of turning on LED using android app). But I do not know how to do it. Is there any example that I can look at?

Best regards,

Kosar

[awneil]

The Central (eg, phone) cannot see the Peripheral unless it is advertising - so there is no way to do this using BLE alone.

karoun said:

Low power consumption is an important consideration

How "low", exactly?

Even when advertising, the time that the radio is actually active is only a small fraction of the total time.

Could you use another wakeup signal; eg, NFC, a tap. etc ?

Choose your advertising parameters carefully - it's a tradeoff between how quickly & reliably the Central can find the device, and how much power you use.

[Karl Ylvisaker]

Hello Kosar,

As awneil said, the central(phone) will not know about the peripherals presence if it is not advertising, but there are many other ways to have the peripheral wake up at different intervals or events.
The chosen wakeup method and advertising parameters will significantly impact the power consumption, but it is also not possible for us to suggest anything in particular without knowing more about the intended application.

If you are looking to go the route of a GPIO wakeup signal, you might be interested in seeing the Pin Change Interrupt example, which demonstrates how to set up an interrupt on pin change. You may also want to have a look at the BLE Blinky app for seeing the basic BLE parts of peripheral implementation.

Best regards,
Karl

[karoun]

Thank you for your reply Karl.

Since the intention is to have an implantable device I do not want to use any physical pin. I see in several discussions in devzone that some are suggesting using single shot timer. I need to get periodic advertisement. for example advertise in some minute and then stop for some other minute and so on...

[awneil]

karoun said:

I do not want to use any physical pin

But does NFC (or similar) remain an option?

karoun said:

advertise in some minute and then stop for some other minute and so on

Sure, you can do that.

[Karl Ylvisaker]

karoun said:

Thank you for your reply Karl.

No problem at all, I am happy to help!
Though I would have to share credit with @Awneil in this case - he has been much swifter on the reply than me! 

karoun said:

I see in several discussions in devzone that some are suggesting using single shot timer. I need to get periodic advertisement. for example advertise in some minute and then stop for some other minute and so on...

For this, you could use the app timer module in repeated mode(not single shot) to have it trigger advertising periodically. App timer usage is demonstrated in many of the examples, for example the Proximity example where it is used to periodically measure battery voltage.
Alternatively, depending on your application, NFC might also be an option for wakeup, as Awneil suggested.

Best regards,
Karl