https://devzone.nordicsemi.com/f/nordic-q-a/10570/target-resetting-when-initalizing-uartI have a strange problem on my target nRF51822. When I try and use the UART interface between my nRF51 and my host MCU, it causes the nRF51 to reset and the RTT terminal to freeze. See the RTT log window capture attached. rttsession.JPG www.dropboxen-USTelligent Community 13Tue, 01 Dec 2015 15:17:37 GMThttps://devzone.nordicsemi.com/thread/39323?ContentTypeID=1Tue, 01 Dec 2015 15:17:37 GMT137ad170-7792-4731-bb38-c0d22fbe4515:99cb5e8f-2a5f-4b79-a51a-2e39b2367a92Ole Bauck<p>Normal configuration for <code>APP_ERROR_CHECK(...)</code> is to reset the chip, most of the times this is the case of periodic resets. If you define DEBUG in the preprocessor symbols <code>APP_ERROR_CHECK(...)</code> will go into while(1) loop instead. If this happens check the variables in <code>app_error_handler(...)</code> (either in debug mode or with RTT).</p><div style="clear:both;"></div>https://devzone.nordicsemi.com/thread/39325?ContentTypeID=1Tue, 01 Dec 2015 09:51:42 GMT137ad170-7792-4731-bb38-c0d22fbe4515:537cb0d9-2a9e-4c88-b86d-415742d18f0aDoug_H<p>It looks like the problem is the target board UART pins are not initialized correctly. If the nRF51 senses incorrect signals on it&#39;s UART Pins it will reset. At least, that&#39;s what I suspect. Doing some more testing to confirm...</p><div style="clear:both;"></div>https://devzone.nordicsemi.com/thread/39324?ContentTypeID=1Tue, 01 Dec 2015 07:53:41 GMT137ad170-7792-4731-bb38-c0d22fbe4515:6ac1bd4d-2fbd-43d9-94eb-275aae2c0ee7Doug_H<p>Doing some more testing. If I change the pins for TX and RX to two unused pins on my target nRF51822, the application no longer resets, so the question is, what kind of hardware signal issue would cause a reset?</p><div style="clear:both;"></div>