LPC1768 USB hangup

John Larkin · 2012-07-07T19:19:04+00:00

We built a little picosecond pulse generator box with a USB interface.The USB is directly into an LPC1768 NXP ARM chip, and we're using theUSB stack and inf file that Code Red provided. It enumerates as aserial port. It's "unsupported", which means it's *really*unsupported.Under Windows XP, there's a small glitch. I can plug/unplug the USBcable, and it always makes all the proper bleep/bloopconnect/disconnect noises. It shows up as COM6 or some such. I cantalk to it from Hyperterminal or from a PowerBasic program. But if Idisconnect the USB cable while the port is open, it hangs up. The fixis to close the program, then go to Device Manager, disable it, andre-enable it.I've seen other USB devices behave this way, too.Anybody know what's going on, and maybe how to fix it?

LPC1768 USB hangup

Jul 07, 2012 22 Replies

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Stephen Pelc 14 years ago

It now turns out that ClearCommError() returns 0 if a USB serial port is disconnected. This fits well with the current Windows documentation. Our terminal emulator now closes the port gracefully when the USB adapter is diconnected.

Stephen

Stephen Pelc, stephenXXX@mpeforth.com MicroProcessor Engineering Ltd - More Real, Less Time 133 Hill Lane, Southampton SO15 5AF, England tel: +44 (0)23 8063 1441, fax: +44 (0)23 8033 9691 web: http://www.mpeforth.com - free VFX Forth downloads

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josephkk 14 years ago

My first guess is that Winders does not properly comply with the USB specification, or that the specification itself has problems with disconnect followed by reconnect. Fortunately the USB specification is publicly available from the USB consortium.

?-)

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Mario 14 years ago

W dniu 2012-07-08 01:00, John Larkin pisze:

Hi. Use terminal v1.9b by Br@y++. It can close virtual port after disconnecting usb cable.

Regards MD

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