nRF52832 External HFXO

RE: nRF52832 External HFXO

MartinBL — Tue, 07 Jun 2016 08:45:27 GMT

Oh, I did. Thank you.

RE: nRF52832 External HFXO

RK — Tue, 07 Jun 2016 08:16:00 GMT

Martin - I think you mixed up HFINT and HFXO in the first paragraph, it's XO you need for the radio and NFC and it's HFXO you manually start if you want it.

RE: nRF52832 External HFXO

MartinBL — Tue, 07 Jun 2016 07:26:13 GMT

Hi,

It is as RK says. HFXO is only required when you are using the radio or NFC, or when you are doing calibration of the internal low frequency 32kHz oscillator (LFRC). The nRF5s will automatically switch between HFINT and HFXO and choose the most power efficient option (unless you manually start the HFXO). So unless you need to control it yourself you don't need to worry about this at all.

What do you mean by "do we use HFINT with 32.768KHz RC oscillator"? You can choose to use LFRC or LFXO. In this case though, it is actually more power efficient to use an external LFXO.

RE: nRF52832 External HFXO

hank2k — Tue, 07 Jun 2016 06:04:48 GMT

But If that case is running BLE not Bluetooth, do we use HFINT with 32.768KHz RC oscillator?

RE: nRF52832 External HFXO

RK — Tue, 07 Jun 2016 02:50:48 GMT

Because the softdevice requires the HF crystal as the internal RC isn't accurate enough for radio operation. So if you are using bluetooth, you need the external crystal .. from the manual

The HFXO must be running to use the RADIO, NFC module or the calibration mechanism associated with the 32.768 kHz RC oscillator.