Tomas Larsson wrote:

>>-----Original Message-----
>>From: piclist-bounces@mit.edu 
>>[mailto:piclist-bounces@mit.edu] On Behalf Of Robert Young
>>Sent: Friday, February 10, 2006 4:03 PM
>>To: 'Microcontroller discussion list - Public.'
>>Subject: RE: [PIC]: Getting started with USB
>>
>>
>>
>>    
>>
>>>-----Original Message-----
>>>From: piclist-bounces@mit.edu
>>>[mailto:piclist-bounces@mit.edu] On Behalf Of Alan B. Pearce
>>>Sent: Friday, February 10, 2006 8:39 AM
>>>To: Microcontroller discussion list - Public.
>>>Subject: Re: [PIC]: Getting started with USB
>>>
>>>
>>>      
>>>
>>>>The FDTI chip normaly emulates a comport,
>>>>        
>>>>
>>>While I agree this is true for the FT232 serial chips, I am
>>>not sure about the FT245. I was assuming it looked like a 
>>>parallel printer port to the OS.
>>>      
>>>
>>No.  There are two drivers available from FTDI, the VCP (Virtual Comm
>>Port) and D2XX native mode drivers.
>>
>>All FTDI chips when used with the VCP drivers look like a 
>>serial port to the PC.  It is also possible to make the 
>>device look like a serial port using the D2XX drivers too but 
>>not nearly as simple.
>>    
>>
>
>Yeah, but the most common application seems to be USB-RS232, and to emulate
>a com-port.
>For those that don't have a comport.
>
>
>One thing though, this type of emulation drives me nuts, I have a number of
>commercial stuff based on the fdti-chip, emulating com-ports, and it seems
>to change com-port each time it's used, its very frustrating.
>  
>
I can explain this.The USB port can't tolerate omething hanging on the 
bus that does not
respond to an enquiry. This will happen if power is removed from a 
USB-based product BEFORE
the USB cable is removed. After several tries, the driver removes that 
channel from the list,
so that NEXT time a new channel has to be setup. That drove me crazy for 
a while.

]--Bob

>
>  
>


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