https://devzone.nordicsemi.com/f/nordic-q-a/22876/uart-heat-problemHi I have working module which communicates via uart with another module. It works good, unless it is heated to 40C. After that temperature UART communication is not correct, there are framing errors etc. What might be wrong with temperature there? Isen-USTelligent Community 13Sun, 18 Jun 2017 15:54:54 GMThttps://devzone.nordicsemi.com/thread/89954?ContentTypeID=1Sun, 18 Jun 2017 15:54:54 GMT137ad170-7792-4731-bb38-c0d22fbe4515:d748a60e-cdc2-4f62-90e7-30f2fa3ab492Turbo J<p>The correct crystal must be present for BLE to work at all - so it will be there in case you used any kind of OEM module. Note that the NRF51x defauls to the internal (R/C?) oscillator which is less precise but also uses less run current.</p><div style="clear:both;"></div>https://devzone.nordicsemi.com/thread/89955?ContentTypeID=1Sat, 17 Jun 2017 13:58:08 GMT137ad170-7792-4731-bb38-c0d22fbe4515:d748add6-a98f-4e1f-9942-23c82a7868bfAstalos<p>Does it mean that I should provide some external cristal oscillator? Or this is just swicthing some internal oscillator mode?</p><div style="clear:both;"></div>https://devzone.nordicsemi.com/thread/89953?ContentTypeID=1Sat, 17 Jun 2017 11:58:05 GMT137ad170-7792-4731-bb38-c0d22fbe4515:cccad5c4-3de1-4e30-95ed-1df6d5297268Turbo J<p>Try using the HFCLK crystal oscillator - the quarz is <em>much</em> more stable across the temperature range.</p> <p>You can use the <code>sd_clock_hfclk_request()</code> softdevice call or <code>NRF_CLOCK-&gt;TASKS_HFCLKSTART=1;</code> if you don&#39;t use a softdevice.</p><div style="clear:both;"></div>https://devzone.nordicsemi.com/thread/89952?ContentTypeID=1Sat, 17 Jun 2017 11:48:48 GMT137ad170-7792-4731-bb38-c0d22fbe4515:6f93d2f4-8d31-494c-9970-3b2629e562afTurbo J<p>Did you check the UART data lines with an oscilloscope?</p><div style="clear:both;"></div>