[8051] Use keil-C simulator and debug problem?

Dear all, Sorry, I just see your reply now.

my code is listed as below, my 8051 is Cast R8051XC2

sbit LED_FPGA_LED7=P1^0;
sbit LED_FPGA_LED6=P1^1;
sbit LED_FPGA_LED5=P1^2;
sbit LED_FPGA_LED4=P1^3;

sbit LED_FPGA_LED3=P0^0;
sbit LED_FPGA_LED2=P0^1;
sbit LED_FPGA_LED1=P0^2;
sbit LED_FPGA_LED0=P0^3;

void Timer0_IntHandler(void) interrupt 1
{
  static U8 u8Count0=0;
  U16 u16tmp=0;
  bit bLedTemp0_BDATA=0;
  U8 u8LedTmp0_IDATA=0; //DATA:0x0~0x7F static U8 u8LedTmp0_XDATA=0;

  EAL = 0; ET0 = 0;

  TH0=0x01;
  TL0=0x55;

  bLedTemp0_BDATA=LED_FPGA_LED7;
  u8LedTmp0_IDATA=LED_FPGA_LED7;
  u8LedTmp0_XDATA=LED_FPGA_LED7;

  bLedTemp0_BDATA=~bLedTemp0_BDATA;
  u8LedTmp0_IDATA=~u8LedTmp0_IDATA;
  u8LedTmp0_XDATA=~u8LedTmp0_XDATA;

  LED_FPGA_LED7=~LED_FPGA_LED7;
  if(0==(u8Count0%5))
  {
    LED_FPGA_LED6=~LED_FPGA_LED6;
  }

  u8Count0++;
  ET0 = 1;
  EAL = 1;
}

void Timer1_IntHandler(void) interrupt 3
{
  static U8 u8Count1=0;
  bit bLedTemp1=0;

  EAL=0;
  ET1=0;

  if(0==(u8Count1%10))
  {
    bLedTemp1=LED_FPGA_LED5;
    LED_FPGA_LED5=(~bLedTemp1);
    //LED_FPGA_LED5=~LED_FPGA_LED5;
  }

  if(0==(u8Count1%15))
  {
    bLedTemp1=LED_FPGA_LED4;
    LED_FPGA_LED4=(~bLedTemp1);
    //LED_FPGA_LED4=~LED_FPGA_LED4; u8StnCount++;
  }

  u8Count1++;
  ET1=1;
  EAL=1;
}

void Timer2_ISR (void) interrupt 5
{
  static U8 u8Count2=0;
  EAL=0;
  ET2=0;

  TF2=0; //clear overflow flag ET2=1; EAL=1;
}

void EX3_ISR (void) interrupt 10
{
  bit bEx3Temp=0;
  EAL=0;
  EX3=0;

  bEx3Temp=LED_FPGA_LED3;
  LED_FPGA_LED3=(~bEx3Temp);
  //LED_FPGA_LED3=~LED_FPGA_LED3;

  EX3=1; EAL=1;
}

void EX4_ISR (void) interrupt 11
{
  bit bEx4Temp=0;
  EAL=0;
  EX4=0;

  bEx4Temp=LED_FPGA_LED2;
  LED_FPGA_LED2=~bEx4Temp;
  //LED_FPGA_LED2=~LED_FPGA_LED2;

  EX4=1; EAL=1;
}

void EX5_ISR (void) interrupt 12
{
  bit bEx5Temp=0;
  EAL=0;
  EX5=0;
  bEx5Temp=LED_FPGA_LED1;
  LED_FPGA_LED1=(~bEx5Temp);
  //LED_FPGA_LED1=~LED_FPGA_LED1;

  EX5=1;
  EAL=1;
}

void EX6_ISR (void) interrupt 13
{
  bit bEx6Temp=0;
  EAL=0;
  EX6=0;
  bEx6Temp=LED_FPGA_LED0;
  LED_FPGA_LED0=(~bEx6Temp);
  //LED_FPGA_LED0=~LED_FPGA_LED0;

  EX6=1;
  EAL=1;
}

I use simulator in Keil-C Q1: The initial value of LEDs all are "1". The interrupt occured sequence is EX3 -> EX4 --> Timer0 ->EX5 ->Timer1 -> EX6 ->Timer0 ->Timer1 my main function is always runnging in while(1){ } loop and doing nothing.

When I use debug mode to trace the changing of LEDs.
After running Timer1-ISR, the all valus of LEDs change correctly.
But after Timer1-ISR and before EX6-ISR I don't know why the LED_FPGA_LED4 changes from 0 to 1.

LED_FPGA_LED7=1 --->0--------->1
LED_FPGA_LED6=1 --->0--------->0
LED_FPGA_LED5=1 ----->0
LED_FPGA_LED4=1 ----->0->1(the problem point, I don't know who changes it.)------->0 (enter Timer1-ISR again, it becomes 0, but who changes it?)

LED_FPGA_LED3=1 ->0
LED_FPGA_LED2=1 -->0
LED_FPGA_LED1=1 ---->0
LED_FPGA_LED0=1 ---------->0

Q2: In the Timer0-ISR, I declares several variables, one of them is u8LedTmp0_IDATA. I found it will be located at DATA:0x7 in running time. But it seems I could not change it's value after u8LedTmp0_IDATA=LED_FPGA_LED7. It always keeps in the same value. After I check the 8051 specification. it says the 0x0~0x1F are work registers for R0~R7. Is it the root casue? How could I set the keil-C and let the 8051 does not use DATA:0x0~0x1F in running time?

Thanks a lot.

  U8 u8LedTmp0_IDATA=0; //DATA:0x0~0x7F static U8 u8LedTmp0_XDATA=0;
As a temporary variable will always be set to 0 at ISR entry
  u8LedTmp0_IDATA=LED_FPGA_LED7;
set to a value never used
  u8LedTmp0_IDATA=~u8LedTmp0_IDATA;
zeroing it out

what are you trying to do? nothing??

I dislike you include IDATA in a label of soething you have no idea where it goes

  bLedTemp0_BDATA=LED_FPGA_LED7;
  u8LedTmp0_IDATA=LED_FPGA_LED7;
  u8LedTmp0_XDATA=LED_FPGA_LED7;

  bLedTemp0_BDATA=~bLedTemp0_BDATA;
  u8LedTmp0_IDATA=~u8LedTmp0_IDATA;
  u8LedTmp0_XDATA=~u8LedTmp0_XDATA;

1. Yes, it does nothing. I just monitor where the variables are placed.
2. About IDATA label , Sorry I forgot to modify it's name. It should be DATA, because this variable(u8LedTmp0_IDATA) will be placed in DATA area.

Which is exactly why you should not have it in the name at all - as Joe said!

Please ignore my Q2. I just know the root cause. Thank you.