Re: Streets & Trips - no USB GPS support help

"Jack Erbes" <jackerbes@xxxxxxxxxxxx> wrote in message
news:MYednRJQF7WOeUvfRVn-hw@xxxxxxxxxxxxxxx
> Meindert Sprang wrote:
>
> <snip post made by some imposter in my name... :>) >
>
> > Jack, such a converter definately does not present a hardware serial
port.
> > The com port that is created, is a virtual port.
> <snip>
>
> Thanks for straightening me out and my apologies to Tom for adding a
> layer of confusion to his post.
>
> I'm not sure where I got that idea. I thought that IC had a UART in it
> (which, in hindsight, is probably not right either) and I guess that
> lead me to think it was a hardware serial port.

Well, the chip does have a UART in it, but unlike the "old" uarts, which
were connected to the ISA bus on an IO address and an interruot, these are
on the USB bus. The USB controller in the PC of course has an IO address and
an interrupt, but these are used to communicate with the USB controller and
to implement a data transport protocol which talks to every connected USB
device.

> Is the fact that none of this is not real the reason that Windows
> handles it so well? :>)

Well, the trouble is that most cheap USB converters are mostly a cheap micro
with USB port and UART, for which the manufacturer has provided a sort of
demo kit with drivers that are mostly in beta stadium and purely meant to be
a demo. The manufacturer of such a converter then takes such a demo kit,
massages it into his own product, only altering the device names and ID in
the chip/driver and starts selling it cheaply. The better ones, mostly more
expensive, are real developed and tested products and perform much better. A
good example are the converters with the FTDI chip. These work with ALL
applications, always. The reason is that this chip is an asic, a chip which
is specifically designed to do the jobs. And since developing/making an asic
is much more expensive than a plain software solution on a cheap
microcontroller, the chance that it is a mature product is much much higher.
I also sell these converters with an FTDI chip, but since I buy them in
small quantities, the retail price is rather high ($60). But it is mostly
not hard to convice the customer that these work for their application,
guaranteed (besides the fact that I supply them with a customized driver,
which blocks Windows PnP requests, resulting in jumping cursors).

Meindert


.

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