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

Dear all, 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; #if 0 if(!(u8Count2%50)){ static U8 u8ShowCount=0; Drv_WriteByteToStn(1,0,0x41+u8ShowCount); u8ShowCount++; }

u8Count2++; #endif 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------->0 (enter Timer1-ISR again, it becomes 0, but who changes it?) |->(the problem point, I don't know 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 not use 0x0~0x1F in running time?

Thanks a lot.