Hi my friends.. I have some trouble with my project. I try to communication microcontroller AT89C51 with computers. I didn't use rs 232, but I replacement with NOT gates. sometimes run and sometimes not run, I don't know why???? mybe you have idea???
Hello, Perhaps a problem with signal levels. RS232 needs a voltage of something around 10 volts for Low and -10 volts for high state on the RxD and TxD lines. I think your inverter puts only 0 volts and 5 volts onto the lines. Sometimes this would work, but the 0 volt level might be the problem for the receiver in your computer. Try to use a different RS232 transceiver, for example MAX232. Jochen
"Try to use a different RS232 transceiver" His problem is precisely that he has not used any RS232 transceiver!