HFCLK (HFXO) failure detection

[santosh athuru]

Hi,

We have below questions regarding HFXO. 

1.> Will softdevice or nordic HW be able to recognize that the 32 MHz crystal is non functional during run time (after the HFCLKSTART task is successful)?

Is there any interrupt or event generated on the fault detection?

2.>  Will the HFCLK be automatically sourced from HFINT when HFXO becomes non-functional during run time? 

3.> In softdevice what happens if HFCLKSTART event doesn't complete?

4.> From section 9.2.5 of S132 SoftDevice specification v6.1:- it is not clear on how the application can request the SoftDevice to have the external high-frequency crystal ready by the start of the timeslot.

Is application required to call some softdevice API to do the HFCLKSTART before softdevice is enabled?

Thanks

Santosh Kumar Athuru

[Simonr]

Hi

The HFCLK is (in most examples) is started by the SoftDevice (in SOFTDEVICE_HANDLER_INIT), which is why you're not able to see the initialization of it. Sorry if I misunderstood, but I thought you wanted to know how you could start the HFCLK if you wanted. If the HFCLK is not available during startup, the SoftDevice will just wait for the HFCLK to become available, which is why the connection is lost and the device is not advertising.

If the application is already running and the HFXO (external HF clock) fails, it apparently does not return an error, and the SoftDevice will keep running (very inaccurately), and ultimately failing due to timing errors or similar.

Best regards,

Simon