On Jan 30, 8:57 pm, Didi <d...@tgi-sci.com> wrote:
> > By _low_ do you mean 0 on the AVR GPIO, sorry just clarifying.
>
> Yes.
>
> > When will RS232 be banned? :- {)
>
> Hah, it is that more or less is already - try to buy a laptop with
> it. :-)
>
> It is still pretty useful for lowest level debugging etc., at the very
> begining of projects or when not all of the stuff is functional.
>
> Dimiter
>
> ------------------------------------------------------
> Dimiter Popoff Transgalactic Instruments
>
> http://www.tgi-sci.com
> ------------------------------------------------------http://www.flickr.com/photos/didi_tgi/sets/72157600228621276/
>
> On Jan 30, 9:57 pm, ratemonotonic <niladri1...@gmail.com> wrote:
>
> > On 30 Jan, 19:38, Didi <d...@tgi-sci.com> wrote:
>
> > > > the problem is that when I set the CTS AVR GPIO high(1) the voltage
> > > > that I see the 9 way connector pin is -5v and when I set CTS AVR GPIO
> > > > to low(0) the voltage on the 9 way connector is 0v.
>
> > > > Is that the expected behavior? I think i am missing some fundamental
> > > > concept.
>
> > > It is the expected behaviour allright if the buffers you use are
> > > inverting (they normally are).
> > > But you need to drive CTS _low_ to enable data flow, not high.
> > > This is how all CTS inputs (past buffers, at TTL level) I have
> > > seen work. :-)
>
> > By _low_ do you mean 0 on the AVR GPIO, sorry just clarifying. When
> > will RS232 be banned? :- {)
Fixed the problem , faulty IC (MAX322). was not raising the voltage up
when GPIO was going low.
thanks for clearing my this out.
BR
rate
Reply by Didi●January 30, 20082008-01-30
> By _low_ do you mean 0 on the AVR GPIO, sorry just clarifying.
Yes.
> When will RS232 be banned? :- {)
Hah, it is that more or less is already - try to buy a laptop with
it. :-)
It is still pretty useful for lowest level debugging etc., at the very
begining of projects or when not all of the stuff is functional.
Dimiter
------------------------------------------------------
Dimiter Popoff Transgalactic Instruments
http://www.tgi-sci.com
------------------------------------------------------
http://www.flickr.com/photos/didi_tgi/sets/72157600228621276/
On Jan 30, 9:57=A0pm, ratemonotonic <niladri1...@gmail.com> wrote:
> On 30 Jan, 19:38, Didi <d...@tgi-sci.com> wrote:
>
> > > the problem is that when I set the CTS AVR GPIO high(1) the voltage
> > > that I see the 9 way connector pin is -5v and when =A0I set CTS AVR GP=
IO
> > > to low(0) the voltage on the =A09 way connector is 0v.
>
> > > Is that the expected behavior? I think i am missing some fundamental
> > > concept.
>
> > It is the expected behaviour allright if the buffers you use are
> > inverting (they normally are).
> > =A0But you need to drive CTS _low_ to enable data flow, not high.
> > This is how all CTS inputs (past buffers, at TTL level) I have
> > seen work. :-)
>
> By _low_ do you mean 0 on the AVR GPIO, sorry just clarifying. When
> will RS232 be banned? :- {)
Reply by ratemonotonic●January 30, 20082008-01-30
On 30 Jan, 19:38, Didi <d...@tgi-sci.com> wrote:
> > the problem is that when I set the CTS AVR GPIO high(1) the voltage
> > that I see the 9 way connector pin is -5v and when I set CTS AVR GPIO
> > to low(0) the voltage on the 9 way connector is 0v.
>
> > Is that the expected behavior? I think i am missing some fundamental
> > concept.
>
> It is the expected behaviour allright if the buffers you use are
> inverting (they normally are).
> But you need to drive CTS _low_ to enable data flow, not high.
> This is how all CTS inputs (past buffers, at TTL level) I have
> seen work. :-)
By _low_ do you mean 0 on the AVR GPIO, sorry just clarifying. When
will RS232 be banned? :- {)
Reply by Didi●January 30, 20082008-01-30
> the problem is that when I set the CTS AVR GPIO high(1) the voltage
> that I see the 9 way connector pin is -5v and when =A0I set CTS AVR GPIO
> to low(0) the voltage on the =A09 way connector is 0v.
>
> Is that the expected behavior? I think i am missing some fundamental
> concept.
It is the expected behaviour allright if the buffers you use are
inverting (they normally are).
But you need to drive CTS _low_ to enable data flow, not high.
This is how all CTS inputs (past buffers, at TTL level) I have
seen work. :-)
Dimiter
------------------------------------------------------
Dimiter Popoff Transgalactic Instruments
http://www.tgi-sci.com
------------------------------------------------------
http://www.flickr.com/photos/didi_tgi/sets/72157600228621276/
On Jan 30, 9:28=A0pm, ratemonotonic <niladri1...@gmail.com> wrote:
> Hi all ,
>
> I am using GPIO lines of an AVR to control the RTS & CTS lines of the
> RS232 interface. The level convertor that I am using is MAX3222.
>
> Software wise when the AVR is configured as a DCE so the RTS line is
> input and CTS is output , the software sets the GPIO going to the CTS
> high as long as it has buffer space , when it is wants the DTE to stop
> sending data it pull the GPIO low.
>
> the problem is that when I set the CTS AVR GPIO high(1) the voltage
> that I see the 9 way connector pin is -5v and when =A0I set CTS AVR GPIO
> to low(0) the voltage on the =A09 way connector is 0v.
>
> Is that the expected behavior? I think i am missing some fundamental
> concept.
>
> BR
> rate
Reply by James Beck●January 30, 20082008-01-30
In article <5c0a9a78-78a7-4d6a-bcff-
909de5f64b3b@j20g2000hsi.googlegroups.com>, niladri1979@gmail.com
says...
> Hi all ,
>
> I am using GPIO lines of an AVR to control the RTS & CTS lines of the
> RS232 interface. The level convertor that I am using is MAX3222.
>
> Software wise when the AVR is configured as a DCE so the RTS line is
> input and CTS is output , the software sets the GPIO going to the CTS
> high as long as it has buffer space , when it is wants the DTE to stop
> sending data it pull the GPIO low.
>
> the problem is that when I set the CTS AVR GPIO high(1) the voltage
> that I see the 9 way connector pin is -5v and when I set CTS AVR GPIO
> to low(0) the voltage on the 9 way connector is 0v.
>
> Is that the expected behavior? I think i am missing some fundamental
> concept.
>
> BR
> rate
>
A low into the MAX should give you a positive voltage and a high a
negative voltage. There should never be a 0V ever. It is not defined.
Reply by ratemonotonic●January 30, 20082008-01-30
Hi all ,
I am using GPIO lines of an AVR to control the RTS & CTS lines of the
RS232 interface. The level convertor that I am using is MAX3222.
Software wise when the AVR is configured as a DCE so the RTS line is
input and CTS is output , the software sets the GPIO going to the CTS
high as long as it has buffer space , when it is wants the DTE to stop
sending data it pull the GPIO low.
the problem is that when I set the CTS AVR GPIO high(1) the voltage
that I see the 9 way connector pin is -5v and when I set CTS AVR GPIO
to low(0) the voltage on the 9 way connector is 0v.
Is that the expected behavior? I think i am missing some fundamental
concept.
BR
rate