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Debug problem

I am using the simulator of the uvision2.
According to the debugger the value of c doesn't change (I am using the serial peripheral) and the debugger never execute the Start_bit = 1; even though the SBUF = 0x46.

char c ;
void SerialPort(void) interrupt 4 using 2
{
      if (RI == 1) {
        c = SBUF;
      if(SBUF==0x46)
        Start_bit = 1;

      RI = 0;
  }
}

Thank you very much

Parents

0 Jon Ward over 22 years ago

The 8051 has a lot of special registers. Each of these has a name: R0 for register 0, A for accumulator, B for the B-register, and C for the carry flag.

When you display or watch the variable c, you are actually watching the carry flag. To watch your variables that have the same name as 8051 registers, you must escape them with a back-quote ('). For example: 'c

Could this be the problem behind c never changing?

Jon
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0 Jon Ward over 22 years ago

The 8051 has a lot of special registers. Each of these has a name: R0 for register 0, A for accumulator, B for the B-register, and C for the carry flag.

When you display or watch the variable c, you are actually watching the carry flag. To watch your variables that have the same name as 8051 registers, you must escape them with a back-quote ('). For example: 'c

Could this be the problem behind c never changing?

Jon
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0 Kobi Hayun over 22 years ago in reply to Jon Ward

This is the extention of the first interrupt function, but steel according to the simulator debugger ArrLen and chr stay with their init values after the assignment
ArrLen = SBUF;

void SerialPort(void) interrupt 4 using 2
{
if (RI == 1)
{
if(ArrLenFlag==0) // The first value.
{
ArrLen = SBUF;
ArrLenFlag = 1;
}
else
{
if(SBUF=='S') // The start char.
{
Start_bit = 1;
SaveData(1000);
SaveData(1000);
}
else
{
chr = SBUF;
SaveData(chr) // Save the data.
}
}
RI = 0;
}
}

Thank for your help

Kobi
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0 erik malund over 22 years ago in reply to Kobi Hayun

what is IE ?
what id SCON ?
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0 Kobi Hayun over 22 years ago in reply to erik malund

The SCON = 0x50;
IE = 1;

Thank you very much for your help
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0 erik malund over 22 years ago in reply to Kobi Hayun

IE = 1 guarantees that you will not get any interrupts. Have a look at <a href="" target="_blank">http://www.semiconductors.philips.com/acrobat/various/80C51_FAM_PROG_GUIDE_1.pdf">the proframmers reference manual</a> and set the SFRs ciorrectly.

Erik
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0 Kobi Hayun over 22 years ago in reply to erik malund

Hi
I finnaly understood that the local variable is changed to zero and didn't stay at zero (which means that it doesn't succcefuly read the SBUF???).
here are all my init values.

    TMOD = 0x20;
    TH1 = 0xFB;          // baud ~19200;
    TR1 = 1;
    SCON = 0x50;
    IE=0x90;
    EA = 1;
    ES = 1;
    REN = 1;
    RI = 0;

void SerialPort(void) interrupt 4 using 2
{
      while(!RI)
      {
       if(ArrLenFlag==0)
       {
        ArrLen = _getkey ();
        ArrLenFlag = 1;
       }
       else
       {
        if(_getkey()=='S')
        {
          Start_bit = 1;
          SaveData(1000);
          SaveData(1000);
        }
        else
        {
        chr = _getkey ();
        SaveData(chr);
        }
       }
       RI = 0;
       TI = 0;
      }
}

Thank you for your help.
Kobi