pic16f628 and virtual com port via usb

wece · Joined: 12 Jan 2004 Posts: 2 Location: Tampere, Finland

hi,

how hard it is to do virtual com port to pc (winxp/win2k) via usb and pic?
meaning that I would like to connect pic with usb to pc and other side of pic rs232 connection so that I could do transparent usb-rs232 adapter.

I know that there are similar ic's to do the jod but I would like to do this with pic so how hard it is and is it even possible?
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Mark · Joined: 07 Sep 2003 Posts: 2838 Location: Atlanta, GA

Well that depends on your skills. If you are not familar with writing drivers for Windows, then you are going to have a rough time. Take a look at FDTI. They have a USB chip that you can connect to a pic to do what you want. They supply the Windows drivers.

alexz · Joined: 17 Sep 2004 Posts: 133 Location: UK

But will you be able to use your own product/company descriptor in this case?
Or it will be the FTDI's one there?
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Alex

asmallri · Joined: 12 Aug 2004 Posts: 1635 Location: Perth, Australia

If you just want transparent USB to RS232 then you do not even need a PIC. The FDTI232 chip, with the supplied drivers, appears to the PC as a serial port including full handshaking. I use the FDTI chips because of their ease of use.

Having said that, I also have a Bitscope (DSO) that has a USB adapter that uses the chip. I recently updated my development system with XP SP2 - when I did this, my Bitscope DSO application, which had been working well for months, stopped working because windows XP suddenly decided it was now a Microsoft Ball Mouse - totally destroyed my desktop in seconds. It was a real pain tryig to disable the Microsoft Ball Mouse driver to recover my DSO. With so many companies incorporating the FDTI chips into their products this problem will get worse.

alexz · Joined: 17 Sep 2004 Posts: 133 Location: UK

So as I can see it is not such a perfect idea to use the FTDI chips, is it?
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Alex

Mark · Joined: 07 Sep 2003 Posts: 2838 Location: Atlanta, GA

If you install the drivers correctly, then it is not a problem.

And yes, yes, yes you can enter your own descriptor provided that you incorporate the serial eeprom in your design.

alexz · Joined: 17 Sep 2004 Posts: 133 Location: UK

Thanks Mark Razz

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Alex

asmallri · Joined: 12 Aug 2004 Posts: 1635 Location: Perth, Australia

[quote="Mark"]If you install the drivers correctly, then it is not a problem.
[\quote]

I disagree. It is easy to get your initial implementation working with the correct drivers but you are at the mercy of subsequent device installations or, as I discovered, during automatic software updates, the working implementation can be broken.

treitmey · Joined: 23 Jan 2004 Posts: 1094 Location: Appleton,WI USA

Also see my note in debugger forum
http://www.ccsinfo.com/forum/viewtopic.php?t=19920

it talks about the CCS ICD-U40 and FTDI chips. and the drivers, and how they SHOULD be opened.

Mark · Joined: 07 Sep 2003 Posts: 2838 Location: Atlanta, GA

PCM programmer · Joined: 06 Sep 2003 Posts: 21708

I don't know if that's a good example. Installing the ICD2 drivers
on Win98 and Win2K systems here at the company was a total pain.
It was immensely more difficult than for any other commerical device.

Mark · Joined: 07 Sep 2003 Posts: 2838 Location: Atlanta, GA

My point was that if you read the instructions and install them before plugging in the device and allowing Windows to "pick" a driver, then you shouldn't have any problems.