J-Link RTT Viewer and VT100 escape codes

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  • J-Link RTT Viewer and VT100 escape codes

    Hi everyone,
    I've developed a serial VT100 console and I use it quite often as a debug interface.
    Recently, I've migrated it to RTT (thanks for the great job, guys) and I've had some issues.

    In my current project, transmission is chunked (let's say a full page is 1000 characters long: every 250ms, 300 chars get sent to RTT. Last chunk is 100 chars, then the page creation process starts over).

    I use RTT Viewer to directly enter debug and view the console. Since many VT100 escape codes I use are not supported (the most important being "Cursor Home", that allows for a live set of label / value pairs), the window keeps switching to the "Log" tab, making it unusable.
    Log shows a sequence of warnings, like:

    WARNING: CSI Parameters truncated.
    WARNING: Erase mode not supported.

    Thus, I tried using a telnet connection, but had the same visualization problems.
    Finally, I tried to manually start a debug session and directly telnet it: it works almost perfectly (there are rare char glitches, but had no time to investigate).

    Summing up, I think that:

    - RTT Viewer should be transparent (meaning that it passes data to a telnet client without changing it), or at least there could be an option to make it transparent
    - in RTT Viewer, in case of warnings, a less intrusive approach would be to have an alert icon in the Log tab, instead of switching to it automatically
    - it would be nice to have a small commandline application that simply starts a debug connection, the way RTT Viewer does (might be scripted into the telnet connection sequence)

    What do you think?

    Thank you very much,
    Alberto Spagnolo

    WeDo Engineering s.r.l.
    Via dell'Oreficeria, 30/P
    36100 Vicenza (VI) - Italy
  • Hi Alberto,

    Thank you for pointing this out. We will change the RTT Viewer to show warnings in a non-intrusive way.

    The Telnet connection option is generally meant to attach to a running debug session and get the RTT output from it instead of opening a second connection to J-Link / target.
    For Telnet you can use any Telnet client of your choice and even create your own application.
    To be able to use RTT via Telnet it would be sufficient to start J-Link Commander and specify the target device (e.g. JLink.exe -device STM32F407IE -if SWD - speed 4000).
    The data sent via Telnet are are transparent and directly sent between host and target.

    Best regards
    Johannes
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