RS232 Tutorial problems

Hi Forum, I have tried to get this tutorial to work:, but without any luck so far. The program is exactly the same as in the tutorial. I have an Arduino UNO.

I have bought the ICL232 because I could not find the MAX3323 in my country. So first question, can the ICL232 be used instead of the the MAX3323? Renesas Electronics Corporation

First I did a loopback test with the Serial cable and tested it using Realterm, and there were no problems. Then I connected the wires in the folowing way:

Arduino pin 6 to pin 12 of ICL232.
Arduino pin 7 to pin 11 of ICL232.

Serial cable pin 2 to pin 14 of ICL232.
Serial cable pin 3 to pin 13 of ICL232.

Serial cable 1,4,6 connected together
Serial cable 7,8 connected together
Serial cable 5 to ground
The capacitors is put in place as well

In Realterm i get output, but the ASCII characters is mostsly above 128 and is mostsly nonprintable. One thing that makes it difficult to debug is that the printed ASCII characters change. Some times it prints one character, and sometimes another. I therefore tried altering the baud rate, but sofar without luck.

The cable is a profilic cable. Realterm is set to no parity, 1 stop bit, no hardware flow control

Any suggestions will be highly appreciated!

  • Kasper

Hi Forum, after some trial and error I found that for sending, 104 µs is working, and for receiving 92µs is working.

If someone can tell me why, I would be glad to know.

104uS is right for 9600, 92uS is outside what one would normally think of as OK so I have no idea how that works.

BTW that link goes to a tute about making a morse code library, how is that relevant to this?