nRF5340-DK (PCA10095) crystal capacitors

[PabloL]

Hi,

I just wander why in the peripheral UART sample for the nRF5340-DK (ncs, SDK 2.7.0), the prj.conf doesn't include the internal capacitor configuration:

prj.conf file:

CONFIG_SOC_ENABLE_LFXO=y
CONFIG_SOC_LFXO_CAP_INT_7PF=y
CONFIG_SOC_HFXO_CAP_INTERNAL=y
CONFIG_SOC_HFXO_CAP_INT_VALUE_X2=20
CONFIG_BUILD_WITH_TFM=y

although in the schematics the crystal does not appear to have external capacitors.

Could you clarify this for me?

Thanks

[Priyanka]

Hi Pablo,

It does not matter the sample, and as long as it's built for the DK, it shouldn't be an issue, because the default configs are already tuned for our DK , and moreover, the internal capacitance of the nRF5340 is usually based on the crystal specs used in the DK. Therefore the internal capacitance setting is often not necessary to adjust manually in code. 

In case you are using a different crystal on your custom board, then you might need to manually set this.

Regards,

Priyanka

[PabloL]

Thank you Priyanka,

I mentioned that sample just to use a simple one.
So in this case we can assume that the crystal should be configured underneath.

Regards,
Pablo

[Priyanka]

Yes, that should be the case

-Priyanka