How to bring micro controller out of sleep mode after a certain amount of ticks on a crystal?

[tyler]

I am writing code that runs on a NRF51822 (to be less specific it runs on a Red Bear Lab BLE Nano). The board has a 32.768khz crystal on it that I want to use to wake up the chip after a certain amount of time. How do I go about bringing the board out of sleep mode after an amount of time that can be set by a variable in code? Are there any tutorials, code examples or documentation for how to do this with Nordic SDK I can look at?

[Bjørn Kvaale]

Hi Tyler! This tutorial could be helpful to answer your question. Also, this devzone case will most likely help you further too. Hope that helps! Cheers, Bjørn

[tyler]

Do you know if it's possible to wake up an nrf51822 from systems off sleep mode using an external lfclk?