ASM+C51

Hi everybody.

Thank you all for your answers.

I am using DK3200. I am using your advices during external interrupt.
The problem is that the CPU is stucked after the reset function.(the reset function is the last function in the interrupt routine).
I need the reset as the last function in the interrupt routine.
In addition I don't want to waste another pin for hardware reset.

Thank you all Kobi

Hi everybody.

Thank you all for your answers.

I am using DK3200. I am using your advices during external interrupt.
The problem is that the CPU is stucked after the reset function.(the reset function is the last function in the interrupt routine).
I need the reset as the last function in the interrupt routine.
In addition I don't want to waste another pin for hardware reset.

Thank you all Kobi

.... I forgot some thing.

I think that the writing to the LCD is the source of the problem.(but I need it)

I am adding the code

void lid_int (void) interrupt 0 using 3	// LID Interrupt
{
  unsigned char *chr_ptr;

  EX0 &= 0x00;//Disable external 0 interrupt
  IE0 &= 0;     // Clear INT0 flag

  P1_2 = 0;    // Disable relay
  PWM_Duty_Cyl(0,255);
  PWM_Duty_Cyl(1,255);
  uPSD_PWM_Disable();
  P3_1 = 0;        // Disable BL motor
  P3_0 = 0;        // Disable turbine motor
  P1_1 = 0;        // disable sensors


  lcd_clear();
  chr_ptr = "THE LID IS OPEN!\n";

  while (*chr_ptr != NULL)
  {
     if (*chr_ptr == '\n')
     {
 	    chr_ptr++;
  	    Cursor_LCD ^= 0x40;     			//goto next line
  	    Cursor_LCD &= 0xC0;     			//return to position 0
	    LCD_reg.LCD_CMD_WR = Cursor_LCD;
     }
     else
     {
        BusyCheck();
        LCD_reg.LCD_RAM_WR = *chr_ptr++;
     }
  }
  while(P3_2 == 0) // Until the LID is open
  {

  }

  (*((const void(code*)(void)) 0x0000 ))();
}

You can't do the software reset from within an ISR because an IRET will never be executed. This means that the 8051 interrupt mechanism will not be reset and no further interrupts of equal or lower priority will be serviced.

You must do your software reset from non-ISR code with all interrupts disabled.

Remember that this method is not a real reset - you are just restarting your code.

Why do you need to do a software reset anyway?

Stefan

"I don't want to waste another pin for hardware reset."

But in your code:

  while(P3_2 == 0) // Until the LID is open
  {

  }

  (*((const void(code*)(void)) 0x0000 ))();

Hi

The Interrupt routine is stucked also if the reset funtion is out of the interrupt routine.
According to my debugging in some situation during the program execution the program is stucked after the while and in some cases the reset is working properly.

The question is why in some cases the program is stucked after the while.


Thanks Kobi

You haven't explained why you want to do this software reset. Perhaps you could restructure your program so that you don't need to do it?

I notice you're doing quite a bit of stuff in your ISR. If you want to make your life a whole lot easier:

1) Don't call functions from ISRs.
2) Don't do anything that takes more than a few tens or hundreds of microseconds in the ISR.
3) Try to avoid modifying multi-byte variables in the ISR.

All of the above can be done safely but require you to be fully aware of all the implications.

The 'usual' structure for a program that handles interrupts is:

In the ISR only do things that are absolutely time critical. Set a bit flag so that the main program loop knows that the interrupt has occurred and can take whatever other action is required.

If you stick to these guidelines you will probably spend a lot less time wondering why your program mysteriously hangs or misbehaves.

Stefan