ESC character in virtual com port example...

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ESC character in virtual com port example...

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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)?

Tx

 

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Specialist V

Hi

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.

mjbcswitzerland_0-1600645473695.png

Regards

Mark
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

 

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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. ..  

Ed

 

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