serial communication does not works between two AT89c512 PI24 microcontroller without max232 weather there is possibilities for communication or we must use max232?
MAX232 or similar is used when a microprocessor should interface with "the world". The RS-232 standard has a wider voltage range allowed and is short-circuit-protected etc.
When two microcontrollers on the same PCB need to communicate, then there is no need for any MAX232 - assuming that the two processors have the same supply voltage and have the supply voltage turned on at the same time. If the voltage used is the same for both processors, then it's normally enough to have a series resistor of a couple of kohm between the two processors to protect from short-circuit in case one of the processors happens to reconfigure the I/O signal so you get two outputs connected to each other.
I connected 1kohm resistor in serial with both txr and rxr still it is not working can u make a little bit clear of it?
I do not know if micro (u) can, but ....
well, who knows. It could be your PIG code or your '51 code or your connections. AH, just remember - becuse of identical names, most routing software tend to connect Tx to Tx instead if Tx to Rx, YES, I got caught on that one once :(.
"it does not work, help" is NOT a substitute for debugging although it seems many believe so.
Erik
No, I can not waste my time to be more clear. Notice the difference in length of your post and mine. You don't waste time writing much - despite this being _your_ problem. Why should I invest time writing more when this isn't my problem?
People respond to facts. You don't post facts. People then don't want to cover all bases just in case.