Omega-vehicle-security OME-PIO-D56 Manuel d'utilisateur télécharger pdf (Page 16)

2.4.3 Initial_high, active_low Interrupt source

If the PC0 is a initial_high, active_low signal, the interrupt service routine

should use INV0 to invert/non-invert the PC0 for high_pulse generation as follows:

(Refer to DEMO4.C)

Initial setting:

now_int_state=1; /* initial state for PC0 */

outportb(wBase+0x2a,0); /* select the inverted PC0 */

void interrupt irq_service()

{

if (now_int_state==1) /* now PC0 is changed to LOW */(a)

{ /* --> INT_CHAN_0=!PC0=HIGH now */

COUNT_L++; /* find a LOW_pulse (PC0) */

If((inport(wBase+7)&1)==0)/* the PC0 is still fixed in LOW */

{ /* Æ need to generate a high_pulse */

outportb(wBase+0x2a,1);/* INV0 select the non-inverted input */(b)

/* INT_CHAN_0=PC0=LOW --> */

/* INT_CHAN_0 generate a high_pulse */

now_int_state=0; /* now PC0=LOW */

}

else now_int_state=1; /* now PC0=HIGH */

/* don’t have to generate high_pulse */

}

else /* now PC0 is changed to HIGH */(c)

{ /* --> INT_CHAN_0=PC0=HIGH now */

COUNT_H++; /* find a HIGH_pulse (PC0) */

If((inport(wBase+7)&1)==1)/* the PC0 is still fixed in HIGH */

{ /* need to generate a high_pulse */

outportb(wBase+0x2a,0);/* INV0 select the inverted input */(d)

/* INT_CHAN_0=!PC0=LOW --> */

/* INT_CHAN_0 generate a high_pulse */

now_int_state=1; /* now PC0=HIGH */

}

else now_int_state=0; /* now PC0=LOW */

/* don’t have to generate high_pulse */

}

if (wIrq>=8) outportb(A2_8259,0x20);

outportb(A1_8259,0x20);

}

PC0

INV0

INT_CHAN_0

(a) (b) (c) (d)

OME-PIO-D56/PIO-D24 User Manual (Ver.2.1, Oct/2003, PPH-005-21) ---- 14

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