Matlab to 8051 communication

There also exists USB-to-serial cables that delivers logic-level signals. This type can be found with 3.3V or 5V logic levels and can then be connected directly to the processor pins.
these are so rare that I doubt you have one such (if you bought it in a computer store it is not), so the rest of this post is based on you do not have a such.

If you have a USB-to-serial cable with any internal MAX-chip, then that chip is there to create RS-232 signals, i.e. to create a standard RS-232 port.
so with these signals connected directly to your uC it went pop, blop fizzz ad burned one or both of the Rx and Tx pins.

It doesn't matter if fprintf executed "flawlessly".
this seems to indicate that the Tx pin survived. RS232 levels are such that SOME inputs will correctly catch TTL levels.

Yes, you can use just ground + tx on the cable,
if you did it went pop, blop fizzz ad burned one or both of the Rx and Tx pins.

Put A MAX232 (equivalent) on your board, replace the uC and buy a new cable.

In the unlikely event it 'works' after just adding the MAX232(equivalent) STILL replace the uC and buy a new cable. The previous persom that I know of that 'forgot' the MAX232 did not buy new parts because "evrything worked" later he spent a very long time debugging because the weakened parts finally broke (went intermittent)

Erik

There also exists USB-to-serial cables that delivers logic-level signals. This type can be found with 3.3V or 5V logic levels and can then be connected directly to the processor pins.
these are so rare that I doubt you have one such (if you bought it in a computer store it is not), so the rest of this post is based on you do not have a such.

If you have a USB-to-serial cable with any internal MAX-chip, then that chip is there to create RS-232 signals, i.e. to create a standard RS-232 port.
so with these signals connected directly to your uC it went pop, blop fizzz ad burned one or both of the Rx and Tx pins.

It doesn't matter if fprintf executed "flawlessly".
this seems to indicate that the Tx pin survived. RS232 levels are such that SOME inputs will correctly catch TTL levels.

Yes, you can use just ground + tx on the cable,
if you did it went pop, blop fizzz ad burned one or both of the Rx and Tx pins.

Put A MAX232 (equivalent) on your board, replace the uC and buy a new cable.

In the unlikely event it 'works' after just adding the MAX232(equivalent) STILL replace the uC and buy a new cable. The previous persom that I know of that 'forgot' the MAX232 did not buy new parts because "evrything worked" later he spent a very long time debugging because the weakened parts finally broke (went intermittent)

Erik

The USB-to-serial with logic level output are most definitely not sold in normal computer shops.

It's something like
www.ftdichip.com/.../USBTTLSerial.htm

If there is a standard 9-pin RS-232 connector on the cable, then it is not supplying logic levels, and a MAX232, MAX3232 or similar is needed.

"these are so rare"

Nonsense!

They are widely available from both "mainstream" and "hobby" electronics/robotics distributors.

"Break-out" boards & modules are also widely available to give the same function; eg,

www.sparkfun.com/.../718

thank u for replying...now is this program okay???

#include<reg51.h>
sbit mlp=P1^0;
sbit mln=P1^1;
sbit mrp=P1^2;
sbit mrn=P1^3;
void main(void)
{
  char i='\0';
  SCON=0x50;  // to receive and transmitt serially
  TMOD=0x20;   // timer in mode 2 8 bit auto reload mode
   TH1=-3;   // baud rate 9600
   TR1 = 1;
   while(1)
     {

           if(TI==1)
                {       TI=0;


                        }
                else if(RI ==1)
                        {
                                i=SBUF;

                if(i=='S')
                {
                mlp=mrp=1;
                mrn=mln=0;
                }
                else if(i=='L')
                {
                mlp=mrn=1;
                mrp=mln=0;
                }
                else if(i=='R')
                {
                mlp=mrn=0;
                mrp=mln=1;
                }
                else
                {
                mlp=mrn=0;
                mrp=mln=0;
                }
                RI=0;

                        }




           }
}

i still dint get the o/p...i have a cheap usb to serial converter along with transreceiver and my friend said he even did interrupts with this cable....so i dnt tink that wd be a problem....
and i didnt chk o/p of serial com still to do....tel me f dis prog is okay??? also for serial communication do we have to mess with dat ale and psen pins...or anything out of ordinary u wd do for normal line follower???

also please note that all the above program...simulated prefectly in keil....

dnt tink wd chk tel f dis prog dat u wd

I will copy your idea saving on typing and type 'no' instead of 'yes'

Erik