UART of AT89C51 is not working ?

if it works in simiulation but not in 'real life' the obvious conclusion is a hardware problem

questions
1) I hope you are not one of those that believe that you can do RS-232 without a MAX232(equivalent)?
2) do you have a scope?
3) does hyperterminal give garbage or nothing when the uC send to it?

Erik

if it works in simiulation but not in 'real life' the obvious conclusion is a hardware problem

questions
1) I hope you are not one of those that believe that you can do RS-232 without a MAX232(equivalent)?
2) do you have a scope?
3) does hyperterminal give garbage or nothing when the uC send to it?

Erik

Well i know that i cannot communicate MCU without MAX232, and i have little knowledge about the MCUs cuz i have built one AT89C4051 with successful UART . but dont know the problem .. well as its my own created circuit so there might be problem and one thing that where do i send the Schimitics ?

and there is a garbage on the Hyper terminal....
and one more problem is that when ever i give power to my circuit all the LED's connected to my MCu are ON but they might have to be OFF cuz i have programmed them to be OFF until communication over UART .........
ant Garbage is comming when ever u RST the MCU.

there is a garbage on the Hyper terminal....

that, most often is a result of baud rate mismatch.

well i have found the problem that was on MAX232 cuz its groung was not properly connected....

but there is one more problem that scanf is not working this is what i have written in keil

SCON  = 0x50;
TMOD |= 0x20;
TH1   = 0xf3;
TR1   = 1;
TI    = 1;

printf("Enter the Meter no ");
printf("and Shut down command\n ");
printf("meter: ");
scanf("%d",&i);

well on Hyperterminal all the printf words are shown but dont know why the scanf is not working cuz cursor is not getting any thing from me... why?

"cursor is not getting any thing from me"

Pardon??

why don't you try this type of loop for input.

char InputfromSerial (void)
{ while(!RI);
RI=0;
i=SBUF;
return i;
}

why don't you try this type of loop for input.
and make everything come to a screeching halt when no input arrives.

see a psychriatist aboy your interruptifobia

Erik

Well the problem is solved cuz it was error in connection (Well cuz i am dumb) when i have set the flow control to none it worked like dream ............ but could any one tell me that why My mcu is giving the output 1 as 3 volt-dc but i think it might suppose to be be 1 for 5 volt-dc ?