https://devzone.nordicsemi.com/f/nordic-q-a/57758/uart-overrun-handling-fifoHi We&#39;ve some trouble with the UART (not UARTE) of the nRF52840. We use a baudrate of 38400. Because of HW limitations and power constrains, we do either have flow control nor DMA. We use currently the SDK Version 15.2. Under some circumstances, anen-USTelligent Community 13Thu, 13 Feb 2020 09:09:19 GMThttps://devzone.nordicsemi.com/thread/234121?ContentTypeID=1Thu, 13 Feb 2020 09:09:19 GMT137ad170-7792-4731-bb38-c0d22fbe4515:3f80c789-6ded-454e-86c1-8720d2b0efe0Turbo J[quote userid="74761" url="~/f/nordic-q-a/57758/uart-overrun-handling-fifo"]his because the softdevice will sometimes block the irq of the UART s[/quote] <p>Try raising the UART IRQ priority to APP_IRQ_PRIORITY_HIGHEST.</p> <p>The highest prio available to the app can actually preempt some non-timing critical softdevice tasks. This may (or may not) be enough for 38k baud.</p> <p></p> <p>UARTE and UART sould have roughly similar power consumtion. Both need HFCLK running for proper UART timing.</p><div style="clear:both;"></div>