A few questions about getting started with crystals.

RE: A few questions about getting started with crystals.

run_ar — Wed, 17 Jan 2018 07:22:27 GMT

If you are using an external crystal you need to change the NRF_SDH_CLOCK_LF_XTAL_ACCURACY in sdk_config.h. to switch between external and rc change NRF_SDH_CLOCK_LF_SRC
When the Softdevice is enabled it will turn the HF xtal on/off, so it is only enabled when it is needed for radio communication.

nemunoz — Tue, 16 Jan 2018 20:03:04 GMT

Thank you, run_ar!

I guess I have to switch the crystal settings every time I change the test board.

Sorry, but I have a few more questions:

Is the code (which is in the three post I put before) enough to use with crystals (to program and change between them)?
In your last sentence: "Note that the Softdevice will turn this on/off when need be". Does it means I don't have to care to turn off the High Frequency crystal? And, when SoftDevice is used, SoftDevice will turn it on?

run_ar — Tue, 16 Jan 2018 12:14:51 GMT

Yes, you can. but you have to change the settings to match the board you are using. i.e. if the DK has a 20ppm 32KHz crystal and the custom board has a 40ppm, this needs to be changed.
Use the Higher setting. this is used to determine how early it rx window should start to account for drift. You can use the typical setting if your board will only operate in the typical scenario, if not use the higher setting.
The internal RC requires less external compononents at the cost of increase inaccuracy, so the power consumption will be slightly higer due to a larger listening window and calibration at regular intervals using the HF clock. The external crystal is usually more accurat and does not require calibration. So if you need the lowest power consumption possible you use a crystal, but if cost is more important you can use the internal RC. For the High Frequency clock and external crystal is required for the radio. Note that the Softdevice will turn this on/off when need be.