Sudden error with J-Link RTT Viewer: "WARNING: Sent 15 of 89 bytes

[Elm]

Hi,

I am developing a program on a Nordic nRF51 DK, using Eclipse/gcc, and am using J-Link RTT for a debug command line interface. This has worked very well for some time, but now I have a problem: When I type a command, the "Log" tab of the j-Link RTT Viewer opens and there is a message: "WARNING: Sent 15 of 89 bytes." The first number is always 15, and the second varies with the length of the command. Commands longer than 15 bytes gives this answer, commands shorter than 15 bytes seem to work.

I am totally at loss. I realize that my own program is the major suspect, maybe an astray pointer. Possibly, there is some error with the RTT code from Segger/Nordic. Another thing is that my program now is now close to 64kB, and it might be some 16/32-bit address error. I have not configured RTT in any way, just called SEGGER_RTT_Init().

I would like to know what causes this error in the RTT Viewer, so I can use this information to debug my code. Any help appreciated.

regards, //Elm

[RK]

What's the size of the down buffer you have configured for Segger RTT? I think the default is 16 bytes, with one possibly used as the wraparound byte on the ring buffer, giving you a capacity of 15. That would indicate to me that you're not reading them fast enough, or you're writing them too fast, the buffer fills up and SEGGER RTT gives you a helpful error message.

Try writing slower, reading faster, or giving yourself a larger down buffer, it's all in the RTT config file.

[Elm]

Hi, Reading faster (every 20ms instead of every 100ms) did not work. Increasing the down buffer to well over maximum length of command did not work either.

Sigh. Elm

[RK]

time to hit the Segger forums and see if someone there can explain what the error message is telling you as Segger wrote it and clearly it's coming from the RTT client.

[Elm]

Did that: forum.segger.com/index.php

As of now, no useful info.