Serial line driver (was: TWS Interface)

Archiver

This brings up a question I had. For short runs, do I need a MAX23x
chip? I guess this depends on the application (and hardware) but I
recently hooked up my stamp to my serial port. Between the serial
port's TX bin and a stamp pin I used a 22K resistor. And I went
straight from the stamp to the serial port's RX pin.

Communcation worked well in both directions.

So is this just a question of needing a line driver when the some
certain serial port input truely needs the higher voltages, or when one
needs the higher voltages for cable length considerations?

thanks,

Kevin

Paul Contino wrote:
>
> I would recommend a MAX233 -- no external capacitors necessary.
>
> Paul
>
>

---

Original Message

---

> From: <Newzed@a...>
> To: <basicstamps@yahoogroups.com>
> Sent: Monday, March 26, 2001 4:20 PM
> Subject: [noparse][[/noparse]basicstamps] TWS Interface
>
> > I want to communicate with a Stamp from my PC keyboard via an RF link.
> >
> > I need software that will let me send keystrokes directly to the serial
> port.
> >
> > I need to know how to connect an interface IC - the Max232 - between the
> > serial port and the TWS input. The interface will be used for Transmit
> only.
> >
> > Thanks
> > Sid
> >
> >
> >
> > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
> >
>
>
>
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/

Archiver

Kevin, can you output keystrokes directly to the serial port? That is the
software I need. If your idea works going to a stamp it should work going to
the TWS transmitter.

Sid

Archiver

You can convert a PS/2 keyboard to serial with a PAK-VI:
http://www.al-williams.com/awce/pak6.htm

Regards,

Al Williams
AWC
* NEW: PAK-II now computes polynomials:
http://www.al-williams.com/awce/pak1.htm#poly

>

---

Original Message

---

> From: Newzed@a... [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=070e2bLrt6tC2QTKSRpEjUwXwSePX7rZ4BpuLeFJSrcdlBXHL5icf7vRweOBnK1XGsWmj6eKeGl_]Newzed@a...[/url
> Sent: Monday, March 26, 2001 6:29 PM
> To: basicstamps@yahoogroups.com
> Subject: Re: [noparse][[/noparse]basicstamps] Serial line driver (was: TWS Interface)
>
>
> Kevin, can you output keystrokes directly to the serial port?
> That is the
> software I need. If your idea works going to a stamp it should
> work going to
> the TWS transmitter.
>
> Sid
>
>
>
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
>

Archiver

Didn't we talk about this?

For some small tests communicating to stamps and PICs I just used
HyperTerm. HyperTerm sends keystrokes directly to your serial port.
So, the TWS-434 doesn't really care what's sending it data. You could
connect it directly to your serial port (make sure you use a resistor
since the TWS-434 can only handle 5V vs. your serial port's 12V, don't
nuke your transmitter).

That said, it'd be a bit more work than just using HyperTerm. For
reliable RF communications I've had to make sure I sent a 'warm up' byte
followed by some preamble data to sync the data. I guess you could
always type things like that in by hand (never tried it), but that's not
a very user friendly interface.

Maybe get yourself a book on parallel port programming, I've heard it's
easier and it's already at TTL levels.

Sid, what exactly are you trying to build/accomplish, maybe there's a
ready made solution for you out there?

Kevin

Newzed@a... wrote:
>
> Kevin, can you output keystrokes directly to the serial port? That is the
> software I need. If your idea works going to a stamp it should work going to
> the TWS transmitter.
>
> Sid
>
>
>
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/