Target resetting when initalizing UART

[Doug_H]

I 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.dropbox.com/.../rttsession.JPG

The problem occurs if I either uncomment this line of code

 //UNUSED_VARIABLE(app_uart_get(&data_array[index]));

in the UART event handler function:

Or when I try and initialize the UART. Everything else on my custom target board works perfectly.

I'm attaching the full source file in case someone can see the problem: main.c

Thanks in advance for any ideas!

[Doug_H]

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?

[Doug_H]

It looks like the problem is the target board UART pins are not initialized correctly. If the nRF51 senses incorrect signals on it's UART Pins it will reset. At least, that's what I suspect. Doing some more testing to confirm...

[Ole Bauck]

Normal configuration for APP_ERROR_CHECK(...) is to reset the chip, most of the times this is the case of periodic resets. If you define DEBUG in the preprocessor symbols APP_ERROR_CHECK(...) will go into while(1) loop instead. If this happens check the variables in app_error_handler(...) (either in debug mode or with RTT).