Problems to get the RTT SWD output in a custom board.

RE: Problems to get the RTT SWD output in a custom board.

nemunoz — Tue, 23 Jan 2018 11:34:48 GMT

Yeah! it worked!

So the problem was I didn't configure the crystals for my custom board.

The fact is I saw that question before but to see how to configure, program and use the crystals. I didn't figure out this could be a problem to get an output from a terminal, especially after seen that some components were working.

Thank you so much, AmbystomaLabs!

RE: Problems to get the RTT SWD output in a custom board.

AmbystomaLabs — Mon, 22 Jan 2018 21:48:17 GMT

Since you are using the SWD ports on the DK and have successfully loaded your app code, you have a working SWD/RTT port by virtue of the segger chip on the DK which is what routes the SWD to USB.

So, no need to have a segger on your board as long as you use the DK or a J-Link programmer for SWD.

RE: Problems to get the RTT SWD output in a custom board.

AmbystomaLabs — Mon, 22 Jan 2018 21:44:22 GMT

Can you be certain that the code is executing correctly just from the LED activity?

Clock config issues can keep your code from executing and installing the RTT function which is not native to the SWD port. It is possible some aspects of RTT support are not running yet your LED activity is still the same.

Here is a blog entry where someone had precisely that type of problem: devzone.nordicsemi.com/.../

RE: Problems to get the RTT SWD output in a custom board.

nemunoz — Mon, 22 Jan 2018 20:02:24 GMT

Maybe I'm confusing UART with RTT a little bit, but I'm sure I'm using RTT because in sdk_config.h file I have checked NRF_LOG_BACKEND_RTT_ENABLED and unchecked NRF_LOG_BACKEND_UART_ENABLED.

Also, I followed the tutorial to getting started with RTT and in that tutorial doesn't say if I have to change something to use RTT with a custom board.

You say there is a Segger chip on developer board for virtual SWD comms. So, if there is not that chip on the custom board, I can't use RTT?

RE: Problems to get the RTT SWD output in a custom board.

AmbystomaLabs — Mon, 22 Jan 2018 17:10:44 GMT

I think you are confusing standard UART terminal sessions and Segger RTT. RTT uses SWD for its communications path and does not require UART. And, SWD comms are not on gpio but are dedicated pins on nRF.

The segger chip on the DKs provides for virtual SWD comms and also a virtual UART. RTT uses SWD but it sounds like you were actually using UART for logging/debug info and when you switched to your custom board you lost the virtual UART connection that the DKs provide.

At this point you will either have to provide for the UART path from your custom board or you will need to go through the process to correctly setup RTT.

Here is some info on RTT:

devzone.nordicsemi.com/.../