In the NRF52-DK user guide, the following is stated:
Important: When using ANT/ANT+, the 32.768 kHz crystal (X2) is required for correct operation.
However, I could not find any mention of this in the S332 v2.0 SDS specification (the latest available...) or anywhere else
I have tested making an ANT master on a hardware without a LFXO, and ANT seems to work fine with the LFCLK configured as such:
// <o> NRF_SDH_CLOCK_LF_SRC - SoftDevice clock source. // <0=> NRF_CLOCK_LF_SRC_RC // <1=> NRF_CLOCK_LF_SRC_XTAL // <2=> NRF_CLOCK_LF_SRC_SYNTH #ifndef NRF_SDH_CLOCK_LF_SRC #define NRF_SDH_CLOCK_LF_SRC 0 #endif // <o> NRF_SDH_CLOCK_LF_RC_CTIV - SoftDevice calibration timer interval. #ifndef NRF_SDH_CLOCK_LF_RC_CTIV #define NRF_SDH_CLOCK_LF_RC_CTIV 16 #endif // <o> NRF_SDH_CLOCK_LF_RC_TEMP_CTIV - SoftDevice calibration timer interval under constant temperature. // <i> How often (in number of calibration intervals) the RC oscillator shall be calibrated // <i> if the temperature has not changed. #ifndef NRF_SDH_CLOCK_LF_RC_TEMP_CTIV #define NRF_SDH_CLOCK_LF_RC_TEMP_CTIV 0 #endif // <o> NRF_SDH_CLOCK_LF_XTAL_ACCURACY - External crystal clock accuracy used in the LL to compute timing windows. // <0=> NRF_CLOCK_LF_XTAL_ACCURACY_250_PPM // <1=> NRF_CLOCK_LF_XTAL_ACCURACY_500_PPM // <2=> NRF_CLOCK_LF_XTAL_ACCURACY_150_PPM // <3=> NRF_CLOCK_LF_XTAL_ACCURACY_100_PPM // <4=> NRF_CLOCK_LF_XTAL_ACCURACY_75_PPM // <5=> NRF_CLOCK_LF_XTAL_ACCURACY_50_PPM // <6=> NRF_CLOCK_LF_XTAL_ACCURACY_30_PPM // <7=> NRF_CLOCK_LF_XTAL_ACCURACY_20_PPM #ifndef NRF_SDH_CLOCK_LF_XTAL_ACCURACY #define NRF_SDH_CLOCK_LF_XTAL_ACCURACY 0 #endif
This is with SDK 14.2.0 and S332 v5.0.0
I know for a fact that the softdevice refuses to run if the HFXO is not there, but it seems to be happy to run the ANT stack without a LFXO, so what is the conclusion here?
