Jan Kandziora wrote on 1/2/2007 08:20:
Am Donnerstag, 1. Februar 2007 00:39 schrieb George M. Zouganelis:
Simon Natterer wrote on 1/2/2007 01:16:
George M. Zouganelis wrote:
Today I built a DS2480 serial adapter (schematic attached) after
failing to work with
a orginal Elektor schematic (wich had no RS232 level Driver)(Issue
Apr/2004 By Luc Lemmens)
I have almost the same schematic, but with a MAX232 and there I have to
tie the POL pin to +5V (VDD). I don't know what is the difference of
your ADM232.
Arghhhh!!!! ^^^^^^^^^^^^^^^^^
Remind me to pay you a beer! :D
In the DS2480 datasheet, the following is stated:
6 POL RXD/TXD Polarity Select. RXD/TXD polarity select; tied to GND for
RS232
(12V or 5V) connection; tied to VDD for direct connection to UART chip.
Sorry I lead to certain misconception with the eagle library you used (I
think). There I've written:
The RxD and TxD lines are operated at 0V/5V. The POL pin selects the
RxD and
TxD "polarity", that means straight-through or inverted. If POL is
connected
to GND, RxD and TxD behave properly for connection to inverted RS232
drivers,
like the MC1488/1489 or MAX23x chips. If POL is connected to Vdd, RxD
and TxD
behave properly for direct connection to a 0V/5V UART chip.
So the POL pin should be connected to GND if a simple
diode/transistor/resistor network is is used as the RS232 "interface", like
the Elektor schematic presumably does. If inverted drivers are used in the
peripheral, they are used on *both* sides (computer and peripheral), so the
inversion is gone and POL need to be connected to Vdd.
I had caressly left the POL to GND, extending the Elektor schematic :(
MAX232, translates the -12V for '1' and +12V for '0' to +5v for '1'
and 0V for 0 (MPU/TTL compatible), so on the DS2480 side, -12V has
become TTL logic high (+5V) and +12V has become TTL logic 0 (0V).
Now, it sounds clear to me that POL should be connected to Vdd when
dealing with TTL logic inputs (+5V for logic '1') or GND if we are
conneted to RS232 protocol voltages (-5V or -12V for logic 1).
If this is correct, that's what I would like to read on DS2480 specs. Unless I'm
not so familiar with English reading, I find the 11a,b,c figures a bit confusing
concerning the role of UART/uC. I can only be helped reading Figure titles
(DIRECT, +/-5V, +/-12V)
> Hmmm. Maybe I should update the library. Could anyone of the native english
> speakers here come up with an unambiguous text?
>
btw, do you know where I can find a good walkthrough tutorial on editing
library components for Eagle (Schematic and PCB)? I need to modify some
components
(mainly resizing/relocating their PADs)
Hmmm. Maybe I should update the library. Could anyone of the native english
speakers here come up with an unambiguous text?
Kind regards
Jan
begin:vcard
fn:George M. Zouganelis
n:Zouganelis;George
org:Athens University of Economics and Business;Department of Management Science & Technology
adr:;;76, Patission Ave.;Athens;Attica;;Greece
email;internet:gzoug(at)aueb(dot) gr
title:Technical Administrator
x-mozilla-html:FALSE
version:2.1
end:vcard
-------------------------------------------------------------------------
Using Tomcat but need to do more? Need to support web services, security?
Get stuff done quickly with pre-integrated technology to make your job easier.
Download IBM WebSphere Application Server v.1.0.1 based on Apache Geronimo
http://sel.as-us.falkag.net/sel?cmd=lnk&kid=120709&bid=263057&dat=121642
_______________________________________________
Owfs-developers mailing list
[email protected]
https://lists.sourceforge.net/lists/listinfo/owfs-developers
