Software UART for WindowsXP

Hello,

I am trying to test a modem by pinging it with some data at 38400 baud
using an 8N1 format over a serial RS232 link. I was wondering if
someone had code (for WinXp) for a software UART which will do the
same.

Any suggestions/ideas/comments on the same will be most welcome.

Thanks,
~Tanmay Z.

[F'up2 cut down --- Netiquette would have had the OP do that already.]

In comp.arch.embedded tanmay.zargar@gmail.com wrote:
> I am trying to test a modem by pinging it with some data at 38400 baud
> using an 8N1 format over a serial RS232 link. I was wondering if
> someone had code (for WinXp) for a software UART which will do the
> same.

Now why on earth would you want to do *that*?  If you have a UART, why
not use it?

It's almost certainly not going to work, anyway.  A software-only UART
can be a viable thing to implement on an embedded, narrow-purpose
system where you have complete control over everything the CPU does.

But on a PC running a strictly user-oriented, GUI multitasking system
like XP, there's essentially no way you'll manage to keep sufficiently
precise timing for a software UART to work reliably enough to
meaningfully test some hardware with it.

And that's before you start worrying how, if you don't have a RS232
port, you would ever get the output of that software UART delivered to
the real world.  If you don't have RS232, odds are high you won't have
any freely programmable I/O pins (a.k.a.: a printer port) either.

-- 
Hans-Bernhard Broeker (broeker@physik.rwth-aachen.de)
Even if all the snow were burnt, ashes would remain.

tanmay.zargar@gmail.com wrote:
> Hello,
> 
> I am trying to test a modem by pinging it with some data at 38400 baud
> using an 8N1 format over a serial RS232 link. I was wondering if
> someone had code (for WinXp) for a software UART which will do the
> same.
> 
> Any suggestions/ideas/comments on the same will be most welcome.
> 
> Thanks,
> ~Tanmay Z.
> 
Hyperterminal?

tanmay.zargar@gmail.com wrote:
> Hello,
> 
> I am trying to test a modem by pinging it with some data at 38400 baud
> using an 8N1 format over a serial RS232 link. I was wondering if
> someone had code (for WinXp) for a software UART which will do the
> same.

Are you just trying to capture the output?  If so, I suggest hooking up
to another computers RS232 port and using something like Hyper Terminal
to log transmissions.

Hope that helps,

-- 
Sean

Hans,

I too thought about the timing constraints with a PC. But I was
wondering how HyperTerminal can send the data and that too at rates
higher than 38.4 kBaud. Is this communication reliable in terms of the
accuracy of timing?

Other than that, I have some issues about using HyperTerminal (as some
folks have suggested). I have to transmit 8 bit Hex data. And my
understanding is that HyperTerminal can send only ASCII values. So I
was wondering if there is any way to pack this Hex data into 8 bits and
send it through in an 8N1 format over the RS232.

Any leads, anyone?

T.



Hans-Bernhard Broeker wrote:
> [F'up2 cut down --- Netiquette would have had the OP do that
already.]
>
> In comp.arch.embedded tanmay.zargar@gmail.com wrote:
> > I am trying to test a modem by pinging it with some data at 38400
baud
> > using an 8N1 format over a serial RS232 link. I was wondering if
> > someone had code (for WinXp) for a software UART which will do the
> > same.
>
> Now why on earth would you want to do *that*?  If you have a UART,
why
> not use it?
>
> It's almost certainly not going to work, anyway.  A software-only
UART
> can be a viable thing to implement on an embedded, narrow-purpose
> system where you have complete control over everything the CPU does.
>
> But on a PC running a strictly user-oriented, GUI multitasking system
> like XP, there's essentially no way you'll manage to keep
sufficiently
> precise timing for a software UART to work reliably enough to
> meaningfully test some hardware with it.
>
> And that's before you start worrying how, if you don't have a RS232
> port, you would ever get the output of that software UART delivered
to
> the real world.  If you don't have RS232, odds are high you won't
have
> any freely programmable I/O pins (a.k.a.: a printer port) either.
>
> --
> Hans-Bernhard Broeker (broeker@physik.rwth-aachen.de)
> Even if all the snow were burnt, ashes would remain.

"Tanmay Zargar" <tanmay.zargar@gmail.com> writes:
> I too thought about the timing constraints with a PC. But I was
> wondering how HyperTerminal can send the data and that too at rates
> higher than 38.4 kBaud. Is this communication reliable in terms of the
> accuracy of timing?

The bit-level timing is performed by the serial port hardware, based
on a clock derived from a crystal osciallator.

Depending on the nature of the software that is running, it may or may
not be able to process every receive byte in a timely enough fashion
to avoid recieve overruns.  This is why 16550-style serial ports have
a receive FIFO.

Similarly, if the software is really busy it might not be able to send
bytes at the maximum possible rate.

Tanmay Zargar wrote:
> Hans,
> 
> I too thought about the timing constraints with a PC. But I was
> wondering how HyperTerminal can send the data and that too at rates
> higher than 38.4 kBaud. Is this communication reliable in terms of the
> accuracy of timing?
> 
> Other than that, I have some issues about using HyperTerminal (as some
> folks have suggested). I have to transmit 8 bit Hex data. And my
> understanding is that HyperTerminal can send only ASCII values. So I
> was wondering if there is any way to pack this Hex data into 8 bits and
> send it through in an 8N1 format over the RS232.
> 
> Any leads, anyone?
> 
> T.
> 
>
> 
check out the "ComTestSerial" utility at www.microridge.com.

free download allows you to send and receive binary, ASCII etc up to 
115.2 Kbaud.


Bob

Tanmay Zargar <tanmay.zargar@gmail.com> wrote:

> I too thought about the timing constraints with a PC. But I was
> wondering how HyperTerminal can send the data and that too at rates
> higher than 38.4 kBaud. 

Why, by using a hardware UART, of course!  And one with an internal
FIFO, at that, because at higher baud rates, Windows' interrupt
latency wouldn't even be low enough to deliver one byte at a time
before the next one arrives.

> Is this communication reliable in terms of the accuracy of timing?

Yes.

> Other than that, I have some issues about using HyperTerminal (as some
> folks have suggested). I have to transmit 8 bit Hex data. And my
> understanding is that HyperTerminal can send only ASCII values.

You're confusing the meanings of words.  There's no such thing as "Hex
data" opposed to ASCII values.  There's raw binary data, which may or
not also happen to consist of only ASCII values.

If you want automated high-rate tests, use a programming language to
talk to the serial port.  Pretty much any language should do.

-- 
Hans-Bernhard Broeker (broeker@physik.rwth-aachen.de)
Even if all the snow were burnt, ashes would remain.

ww.fifo.se
AJ

"Fao, Sean" <enceladus311@yahoo.comI-WANT-NO-SPAM> skrev i meddelandet
news:hDB0e.14$MY6.1989@news.abs.net...
> tanmay.zargar@gmail.com wrote:
> > Hello,
> >
> > I am trying to test a modem by pinging it with some data at 38400 baud
> > using an 8N1 format over a serial RS232 link. I was wondering if
> > someone had code (for WinXp) for a software UART which will do the
> > same.
>
> Are you just trying to capture the output?  If so, I suggest hooking up
> to another computers RS232 port and using something like Hyper Terminal
> to log transmissions.
>
> Hope that helps,
>
> -- 
> Sean