Can someone tell me how to make device go to sleep and make it wakeup after a few hous using systick timer. I know how to create a timer but i wanna know which system call is the most efficient.

[Brijesh]

Can someone tell me how to make device go to sleep and make it wakeup after a few hous using systick timer. I know how to create a timer but i wanna know which system call is the most efficient. i know sd_app_evt_wait makes the device in standby mode but it keeps the radio on , I dont wanna use lpn feature but i want that my device sleeps and mesh and ble is deinitialized and it initializes again when the device wakes up with systick timer that i create. I am using nrf52840 and 832  with segger studios.

[Øyvind]

Hello, 

sd_app_evt_wait makes the device in standby mode but it keeps the radio on

Are you certain that you have configured the SoftDevice correctly? When configured correctly, the radio should be able to wake up only when needed and go back to sleep when finished. The SoftDevice uses RTC0 to ensure timing in the system. Which leads to the initial question:

Can someone tell me how to make device go to sleep and make it wakeup after a few hous using systick timer.

RTC (32kHz) is usually used for this kind of applications.  Be aware that the SoftDevice documentation states: "the application must ensure calibration at least once every 8 seconds to ensure +/-500 ppm clock stability.", read more here. 

Have a look at this thread and this thread.

Kind regards,
Øyvind

[Brijesh]

no i am not certaing but isnot it obvious that radio keeps listning to incomming mesages

What i want to acheve is all the devices in the node shud turnoff and wakeup together after some hours,

[Øyvind]

Have a look at the SoftDevice documentation for sd_app_evt_wait(). It states: "The application must ensure that the pended flag is cleared using sd_nvic_ClearPendingIRQ in order to sleep using this function"

Also, have a look at the Power Profiling Application, it includes example use of Low Power Mode and System OFF Mode.

If this doesn't help, have you tried to debug the issue? Making sure that SoftDevice is not giving an error message when going to sleep? Have a look at this tutorial. 

[Brijesh]

I have gone through these documents , My question is when initialise the mesh the node becomes active and radio is always listening to the incomming messages , I want a way to deinitialize and initialize the mesh

[Brijesh]

the device is working fine and sd_evt_wait is returning 0 which means its working fine

but i want the node to be in a state where is doesnot respond to any message form outside.

[Brijesh]

but it shud wakeup when timer ends

[Øyvind]

But to be able to use the built-in timers, you have to use System ON which yields two sub power modes: constant latency or low-power. The latter is the default when entering System ON. 
When running in this mode, System ON, no RAM retention, wake on RTC (running from LFRC clock), you should have a typical current consumption of 1.5µA. More info here.

To turn off everything, System OFF may be your only solution and then have an external timer to trigger after a given timer. The system is reset when it wakes up from the System OFF mode.