LPC Microcontrollersのトピック USB Virtual Com port

USB Virtual Com port

kensu — Thu, 11 May 2017 07:18:35 GMT

Hi,

I have a problem with Virtual com port use.

I build the LPC1857 Virtual com port sample project, it work successfully.

But there is a problem with a procedure.

Step1: Power on 1857, and connect to PC with USB. PC will find a new com port.

Step2: Open Terminal Tool (I use TeraTerm), connect to this com port and start to receive/send data.

Step3: Re-connect USB line(also power RESET 1857), the terminal tool will not receive any data.

Step4: The terminal tool is still connected to this port, I close the terminal program.

Step5: Open terminal tool again, but it cannot find this com port.

In Step5, I check the device manager, the com port is still exist.

I think Step1 to Step4 is correct beahvior for common USB to Com device.

But Step5 is strange, I think the terminal should find the com port again.

Does it cause by firmware or driver? I think it's not terminal tool issue, because I check many common USB-UART port converter, they don't have this issue.

Thanks

Ken

Re: USB Virtual Com port

jeremyzhou — Fri, 12 May 2017 03:07:03 GMT

Hi Ken Su,

Thank you for your interest in NXP Semiconductor products and the opportunity to serve you.

I was wondering if you can tell me the information about your computer.

Did you ever try other terminal tools and can you replicate the issue on your colleagues' PC? And what's the results?

I'm looking forward to your reply.
Have a great day,
TIC

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Re: USB Virtual Com port

kensu — Fri, 12 May 2017 03:47:35 GMT

Hello

Thanks for fast response.

My notebook is Windows 7 professional version (64bit) i5 CPU, Service Pack 1.

After check...

It can replicate for other PC or NB (all windows 7 system 32 or 64 bit).

I also check putty program, and another terminal tool made by C#.

Yes, the situation is same (100%).

Have any comment?

Thanks a lot.

Ken

Re: USB Virtual Com port

jeremyzhou — Fri, 12 May 2017 06:46:46 GMT

Hi Ken,

Thanks for your reply.

I'd highly recommend you can refer to the USB CDC demo which is from the LPC18xx CMSIS-Compliant Standard Peripheral Firmware Driver Library and you may acquire some tips from it.

LPC18xx CMSIS-Compliant Standard Peripheral Firmware Driver Library (Keil, IAR) | www.LPCware.com
Have a great day,
TIC