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Serial Communication w/ AT89C51 or AT89C52

I want to have a simple program to print something out using hyperterminal. Also it would be nice to receive a character and echo it back. I have been able to do this in assembly but I can't get it to work in C. Here is the latest code I have tried:

#include <AT89X51.H> 
#include <CTYPE.H>
#include <STDIO.H>

int i;

void main()
{
SCON = 0x50; //SCON: mode 1, 8-bit UART, enable rcvr
TMOD = 0x20; //TMOD: timer 1, mode 2, 8-bit reload 
TH1 = 0xFD; //TH1: reload value for 9600 baud @ 11.0592MHz 
TR1 = 1; //TR1: timer 1 run 
TI = 1; //TI: set TI to send first char of UART 

while (1) 
{
P1 ^= 0x01; 
printf ("\n\nHello World\n\n"); 
i = _getkey();
putchar('$');
putchar(i); 
}
}

Is there anything wrong with my code? Or is there something in how I am compiling? I am confident my hardware is fine because I can get it to work in assembly. Any help would be appreciated. Thank you.

Parents
  • I reviewed the messages and am not sure whether you tried stepping into your C program using the simulator. I have found this a good tool for both the asynch serial comm and the clocks. The simulator will show you how you have set the baud and will display sbuf.

    Run the simulator with your assy code and record the ports' setup bits. Run again with your C code and compare the ports' setup bits. This may allow you to confirm if you are setting up the ports properly.

Reply
  • I reviewed the messages and am not sure whether you tried stepping into your C program using the simulator. I have found this a good tool for both the asynch serial comm and the clocks. The simulator will show you how you have set the baud and will display sbuf.

    Run the simulator with your assy code and record the ports' setup bits. Run again with your C code and compare the ports' setup bits. This may allow you to confirm if you are setting up the ports properly.

Children
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