[En-Nut-Discussion] RTS-problem

[Harald Kipp]

Hello Csaba,

Are you refering to
http://www.ethernut.de/pdf/ethwm21e-1.pdf
? I remember a bug, but think it's corrected here. If in doubt
about wiring, the most reliable info is provided by the schematic.

For the most simple case, connect pin 4+6 for PORTE2 and

sbi(DDRE, 2);
cbi(PORTE, 2);

to set this line to low. The RS232 driver is inverting and
will output a positive voltage at DB9 pin 8.

However, most of these single supply drivers will not reach
+9 Volts and there's an additional filter resistor RN2B.

I'd suggest to short R30 pads on the backside of the board,
which will route DC power to DB9 pin 9. The voltage will
be about 1.4 Volts below the voltage at the DC connector
due to the voltage drop by two rectifier diodes.

Harald

At 10:50 09.06.2005 +0200, you wrote:
>Hi,
>I have just started with our new Ethernut 2 board. I would like to connect a
>HP34401A multimeter to the serial port of the Enternut and read it through
>the ethernet connector. I use the rs232d.c example to start with.
>
>The multimeter requires +9V on it's DTR leg in order to send data. I thought
>to use the RTS line of the Ethernut board to connect to the DTR pin of the
>multimeter.
>
>I used the info I found in the discussion site archive about HW handshake and
>about setting and clearing bits. Unfortunatelly I could not figure out how to
>change the state of that single line. I do not want a real handshake, only to
>set the RTS line to 1 or 0.
>Does anyone have a suggestion how to do that?
>
>Another question regarding the HW hanshake jumper settings to the rs232
>conector on the board. If you look at the Ethernut Hardware User's Manual
>(pp16), the text and the pictures next to them are not in agreement. Which
>one is right?
>
>Regards,
>Csaba Cserhati
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