ESC character in virtual com port example...

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ESC character in virtual com port example...

Senior Contributor II

I installed the usb_examples/usb_device_cdc_vcom_lite/bm application on my MIMXRT1060-EVK.

When it runs, I can then run a terminal emulator on the host and see the characters echoed back.

The only issue I noticed is that when I type ESC (0x1b) into the terminal the next character is not echoed.  I realize it won't echo back "clean", but I don't understand why the next character is dropped.  I can type other non-printables and they work as expected. I'm running with SDK 2.7.0.  I've used a few different terminal emulators and I see the same things. 

Is there something special about the ESC character in this application (or perhaps in USB)?



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2 Replies

Specialist V


I expect that your problem is that the terminal emulator(s) don't send ESCs.

Try using TeraTerm and sending a file [menu "File | Send File..] containing the sequence you want to test and also setting its file option to binary - this will send all characters.

When I test uTasker CDC in echo mode I get all binary sent and echoed back so it is not a USB restriction in any way.



uTasker project developer for Kinetis and i.MX RT]
Contact me by personal message or on the uTasker web site to discuss professional training or product development requirements


Senior Contributor II

Hey Mark,

Thanks for replying...

Yea, certainly ESC is handled differently, but that wasn't my problem.

My embedded code has a command line editor in it (triggered by ESC).  There was a bug in that code that only shows up when I attempt to run in in virtual-com-port mode.   So prior to isolating that problem (plus the fact that I'm not that familiar with the guts of USB), I thought maybe ESC was "special" in USB. ..  



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