LFCLKSRC crystal PPM accuracy

RE: LFCLKSRC crystal PPM accuracy

Matt Barr — Thu, 04 Dec 2014 00:37:25 GMT

Thank you for the answer Stefan, I appreciate the information on PPM requirements.

RE: LFCLKSRC crystal PPM accuracy

Stefan Birnir Sverrisson — Wed, 03 Dec 2014 14:14:47 GMT

BLE requires 500 ppm in order to be within specification and in order to work. You should sum up all of the accuracy parameters of the crystal to get the total ppm accuracy. If nominal ppm, temperature variation and aging add up to worst case 500ppm or less, that is sufficient for BLE.

ANT has 50ppm reqirement so if you intend to use ANT as well, you should have a higher accuracy crystal.

RE: LFCLKSRC crystal PPM accuracy

Matt Barr — Tue, 02 Dec 2014 16:58:23 GMT

I notice that nRF51-DK projects typically use 20 PPM:

SOFTDEVICE_HANDLER_INIT(NRF_CLOCK_LFCLKSRC_XTAL_20_PPM, false);

The ant examples use 50 PPM:

err_code = sd_softdevice_enable(NRF_CLOCK_LFCLKSRC_XTAL_50_PPM, softdevice_assert_callback);