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Serial port RX Problem - baudrate 9600 setting

athena tsai

I have a strange problem in my code. I cannot receive correct characters via the serial port if I write TH1=0xFD in my code.
But if I write TH1=0xFE in my code, I can run the program correctly.

Why?

Appreciate any response!

athena tsai

-----------------------------------

#include "reg51.h"
#include "stdio.h"

void main (void) { SCON = 0x50;

TMOD |= 0x20;

TH1=0xFE; TR1=1; TI=1; while(1) { unsigned char aaa;

aaa=_getkey();

putchar(aaa); } }

Parents
  • 0 in reply to kalib rahib

    Thans to Kalib Rahib's suggestion.
    My Xtal is 11.059MHz.
    I have modified my code and runing it OK!

    I add a line in my code.
    PCON &= 0x7F; /* Clear SMOD bit -- This Bit double baud rate */
    TH1=0xFD;

    Here is my all code!
    -----------------------------------

    #include "reg51.h"
    #include "stdio.h"

    void main (void) { SCON = 0x50;

    TMOD |= 0x20;
    PCON &= 0x7F;
    TH1=0xFD; TR1=1; TI=1; while(1) { unsigned char aaa;

    aaa=_getkey();

    putchar(aaa); } }

Reply
  • 0 in reply to kalib rahib

    Thans to Kalib Rahib's suggestion.
    My Xtal is 11.059MHz.
    I have modified my code and runing it OK!

    I add a line in my code.
    PCON &= 0x7F; /* Clear SMOD bit -- This Bit double baud rate */
    TH1=0xFD;

    Here is my all code!
    -----------------------------------

    #include "reg51.h"
    #include "stdio.h"

    void main (void) { SCON = 0x50;

    TMOD |= 0x20;
    PCON &= 0x7F;
    TH1=0xFD; TR1=1; TI=1; while(1) { unsigned char aaa;

    aaa=_getkey();

    putchar(aaa); } }

Children
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