nRF52 – steps for logging via RTT to free up UART pins

[mark_pdx]

Hello! I’m using VisualGDB (VS2013, Win7) with an nRF52DK.  Building an app that is a BLE heart rate client, but also needs to use the chip’s UART for controlling an external speech module (only 9600 baud needed, no flow control).

I assume this means I can’t use the Segger “virtual COM port interface” for the nRF_LOG messages while debugging, and need to use RTT instead.  Otherwise all those log messages would interfere with the UART-speechmodule communications.

Can you tell me all the steps for switching the nRF_LOG messages over to RTT, and freeing up the UART for my application?

I’m guessing I need to swap these preprocessor directives in sdk_config.h:

#define NRF_LOG_BACKEND_RTT_ENABLED 0

#define NRF_LOG_BACKEND_UART_ENABLED 1

But in VisualGDB Project Properties>>Embedded Frameworks there’s an option called
Log uses SEGGER RTT

What does this do? It seems to have no effect.

And if I manage to change over to Segger RTT for logging, how do I talk to it?  Can the built in “Raw Terminal” speak to it?

If not, and if I use the J-Link RTT Viewer, won’t that be fighting with Visual GDB for the USB connection to the nRF52DK?

 

I apologize for my confusion. I have experience with Arduino coding, but am a rank beginner at VisualGDB embedded development and have not yet learned about GCC, GDB, makefiles, and all that.  Thanks for your patience!

[support]

Hi,

As we are not a vendor for Segger RTT, unfortunately we cannot provide much help for this. For VisualGDB projects we recommend using our advanced semihosting framework (enabled via the Embedded Frameworks page of VisualGDB Project Properties). It provides fast non-stop semihosting (including support for multiple colors via the ANSI escape sequences), is fully integrated with VisualGDB and doesn’t need any extra setup.

[Author]

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