https://devzone.nordicsemi.com/f/nordic-q-a/57315/using-mdbt50q-u-without-external-32-mhz-crystalHi, I would like to use raytac MDBT50Q-U without an 32 mhz external crystal. Periphal examples like &quot;blinky&quot; work but ble does not? nrf_sdh_enable_request fails with invalid parameter. I am using sdk 15.3 Is it possible to use the module withouten-USTelligent Community 13Tue, 04 Feb 2020 09:23:36 GMThttps://devzone.nordicsemi.com/thread/232483?ContentTypeID=1Tue, 04 Feb 2020 09:23:36 GMT137ad170-7792-4731-bb38-c0d22fbe4515:032a842d-624d-4c01-8ebe-ca31a1ba1f30Andreas48752<p>Thanks, It works now...</p><div style="clear:both;"></div>https://devzone.nordicsemi.com/thread/232478?ContentTypeID=1Tue, 04 Feb 2020 09:11:50 GMT137ad170-7792-4731-bb38-c0d22fbe4515:1e5daa43-9538-4398-9b3b-98703878371fSimonr<p>Hi</p> <p>I assume you refer to the 32<strong>k</strong>Hz not being present in the MDBT50Q-U module, right? The nRF52 will not be able to use the SoftDevice at all without the external 32MHz crystal.&nbsp;</p> <p>When running an example on the internal RC oscillator instead of the 32kHz crystal, the following configurations are recommended.</p> <p><pre class="ui-code" data-mode="c_cpp">// &lt;/h&gt; //========================================================== // &lt;h&gt; Clock - SoftDevice clock configuration //========================================================== // &lt;o&gt; NRF_SDH_CLOCK_LF_SRC - SoftDevice clock source. // &lt;0=&gt; NRF_CLOCK_LF_SRC_RC // &lt;1=&gt; NRF_CLOCK_LF_SRC_XTAL // &lt;2=&gt; NRF_CLOCK_LF_SRC_SYNTH #ifndef NRF_SDH_CLOCK_LF_SRC #define NRF_SDH_CLOCK_LF_SRC 0 #endif // &lt;o&gt; 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 // &lt;o&gt; NRF_SDH_CLOCK_LF_RC_TEMP_CTIV - SoftDevice calibration timer interval under constant temperature. // &lt;i&gt; How often (in number of calibration intervals) the RC oscillator shall be calibrated // &lt;i&gt; if the temperature has not changed. #ifndef NRF_SDH_CLOCK_LF_RC_TEMP_CTIV #define NRF_SDH_CLOCK_LF_RC_TEMP_CTIV 2 #endif // &lt;o&gt; NRF_SDH_CLOCK_LF_ACCURACY - External clock accuracy used in the LL to compute timing. // &lt;0=&gt; NRF_CLOCK_LF_ACCURACY_250_PPM // &lt;1=&gt; NRF_CLOCK_LF_ACCURACY_500_PPM // &lt;2=&gt; NRF_CLOCK_LF_ACCURACY_150_PPM // &lt;3=&gt; NRF_CLOCK_LF_ACCURACY_100_PPM // &lt;4=&gt; NRF_CLOCK_LF_ACCURACY_75_PPM // &lt;5=&gt; NRF_CLOCK_LF_ACCURACY_50_PPM // &lt;6=&gt; NRF_CLOCK_LF_ACCURACY_30_PPM // &lt;7=&gt; NRF_CLOCK_LF_ACCURACY_20_PPM // &lt;8=&gt; NRF_CLOCK_LF_ACCURACY_10_PPM // &lt;9=&gt; NRF_CLOCK_LF_ACCURACY_5_PPM // &lt;10=&gt; NRF_CLOCK_LF_ACCURACY_2_PPM // &lt;11=&gt; NRF_CLOCK_LF_ACCURACY_1_PPM #ifndef NRF_SDH_CLOCK_LF_ACCURACY #define NRF_SDH_CLOCK_LF_ACCURACY 1 #endif</pre></p> <p>Best regards,</p> <p>Simon</p><div style="clear:both;"></div>