https://devzone.nordicsemi.com/f/nordic-q-a/85010/uart-irq-callback-set-causes-crashHi, I have a nRF52833 DK which I&#39;m evaluating for a new product which uses a UART connected GPS receiver. I found some simple UART code which compiles OK, but crashes when uart_irq_callback_set is called. I think I have everything set up OK, soen-USTelligent Community 13Tue, 22 Feb 2022 16:26:24 GMThttps://devzone.nordicsemi.com/thread/354414?ContentTypeID=1Tue, 22 Feb 2022 16:26:24 GMT137ad170-7792-4731-bb38-c0d22fbe4515:68ddf838-85b4-4d05-93f5-df512ff07c84Vidar Berg<p>Hello,</p> <p>Please try the project attached below and see if it results in the same crash. I have not worked with the <a href="https://docs.zephyrproject.org/latest/reference/peripherals/uart.html">UART interrupt APIs</a> before, but from the API documentation it seems like you can only call the send functions inside the UART callback itself. Maybe it is the call to uart_fifo_fill() from main() that causes your program to crash?</p> <p>Test code:</p> <p><a href="https://devzone.nordicsemi.com/cfs-file/__key/communityserver-discussions-components-files/4/7317.simple_5F00_uart.zip">devzone.nordicsemi.com/.../7317.simple_5F00_uart.zip</a></p> <p>This project is one I made only to see if I could replicate the crash your mentioned. If you want a project to use as a reference, then it is probably better that you use the <a href="https://developer.nordicsemi.com/nRF_Connect_SDK/doc/latest/nrf/samples/peripheral/lpuart/README.html">Low Power UART</a> SDK sample.</p> <p>Best regards,</p> <p>Vidar</p><div style="clear:both;"></div>