https://devzone.nordicsemi.com/f/nordic-q-a/15873/uart-irq-stops-firing-after-string-received-and-one-character-transmittedI can send a CR terminated string through the UART using tx fifo OK. BUT, if I receive a string from the UART rx OK first, and then try to send a string, only the 1st character is transmitted through the UART tx, then the uart IRQ stops firing (UART0_IRQHandleren-USTelligent Community 13Wed, 24 Aug 2016 11:30:47 GMThttps://devzone.nordicsemi.com/thread/60558?ContentTypeID=1Wed, 24 Aug 2016 11:30:47 GMT137ad170-7792-4731-bb38-c0d22fbe4515:7adb07a9-d252-4ecf-a7c7-19895a9aa069Ole Bauck<p>Sounds strange. Would you share the code? You can update the question with the code added. You are not running into an error condition, ie ending up in the error handler or resetting?</p><div style="clear:both;"></div>https://devzone.nordicsemi.com/thread/60556?ContentTypeID=1Tue, 23 Aug 2016 17:18:49 GMT137ad170-7792-4731-bb38-c0d22fbe4515:9d74a784-c521-4b6c-9ad6-5916befccd05dcollier8<p>Yes, we are using app_uart_get and app_uart_put, and no we are not using flow control. I increased the interrupt priority, but no difference. I don&#39;t see anything that could block the interrupt (uart) from firing. The receive buffer looks good, btw. Remember sending a string is fine, UNLESS a string is received first.</p><div style="clear:both;"></div>https://devzone.nordicsemi.com/thread/60557?ContentTypeID=1Tue, 23 Aug 2016 12:11:25 GMT137ad170-7792-4731-bb38-c0d22fbe4515:1e602f4a-b329-4374-8700-efe4fabb67deOle Bauck<p>I assume you are using app_uart_fifo.c (and not app_uart.c)?</p> <p>When you receive a byte you should retrieve it from the fifo with app_uart_get(..).</p> <p>Are you doing any other operations in your code that may block the uart interrupt from firing? The uart interrupt will by default run at APP_PRIORITY_LOW. Are you using HW flow control and have you monitored these lines (specifically CTS)?</p><div style="clear:both;"></div>