I am making an 8051 microcontroller communicate wirelessly with a computer. The microcontroller will send a string to its serial port (DB9) and the computer will receive this string and manipulate it.
My problem is that I do not know how to make the 8051 transmit the string just once. Since I need to manipulate the string at the PC end it has to be received only one time. Currently, even though in the C code I am sending the string once, on my computer I am receiving the same string continuously. I assume this is because whatever is in the SBUF is continuously transmitted. Is there any way that I can send my string only once? Is there a way to empty the SBUF?
I tried to use the RTS (Request to Send) pin (7th pin) on the DB9 because I read somewhere that if I negated the voltage on that pin it would stop the flow of data to the serial port. So what I did was programmed my microcontroller to send the string and then sent logic level 0 to an output pin that was connected to my DB9 RTS pin. However, that didn't work.
Does anyone have any suggestions? I'd really appreciate them.
EDIT
The software that I'm using on the PC is X-CTU for Xbee modules. This is the code on my microcontroller:
include reg51.h
void SerTx(unsigned char);
void main(void)
{
TMOD = 0x20;
TH1 = 0xFD;
SCON = 0x50;
TR1 = 1;
SerTx('O');
SerTx('N');
SerTx('L');
SerTx('Y');
}
void SerTx(unsigned char x)
{
SBUF = x;
while(TI==0);
TI = 0;
}
Could someone please verify that it is in fact only sending the string once?
EDIT
Looks like Steve, brookesmoses and Neil hit the nail on the head when they said that it was what was happening AFTER my main function that was causing the problem. I just tried the suggested code Steve put up (more specifically the for(;;); and defining serTX outside of main) and it worked perfectly. The controller is probably rebooted and hence the same code keeps repeating itself.
Thanks so much for the help! :)