Hiya,

Yes.  You can demonstrate this in the simulator as well.

GIE = 1;
T0IE = 0;
T0IF = 1;

Interrupt handler not invoked.

T0IE = 1;

Interrupt handler will be invoked.

myke
----- Original Message -----
From: "Michael A. Powers" <mapowers@IEEE.ORG>
To: <PICLIST@MITVMA.MIT.EDU>
Sent: Tuesday, August 27, 2002 10:55 PM
Subject: [PIC]: Interrupt Enable Flags - quick question


> Thanks Myke, but perhaps I didn't do a good job phrasing the question.
What
> I meant to say is if the following condition exists:
>
> Enable Bit: 0
> Flag Bit: 1
>
> and then, Enable Bit -> 1
>
> will the interrupt be called?
>
>
>
>
> ----- Original Message -----
> From: "myke predko" <myke@PASSPORT.CA>
> To: <PICLIST@MITVMA.MIT.EDU>
> Sent: Tuesday, August 27, 2002 10:40 PM
> Subject: Re: [PIC]: Interrupt Enable Flags - quick question
>
>
> > Hi Michael,
> >
> > To put what you are asking a different way, if the "E" bit for an
> interrupt
> > source is reset (equal to zero) and the interrupt request is received
> > (setting (equal to one) the "F" bit), is the interrupt acknowledged (ie
> jump
> > to address 4 and execute the interrupt handler)?
> >
> > The answer is no.
> >
> > You can test this out in the simulator - Enable TMR0 to run from the
> > internal clock (ie write 0x0D0 to OPTION_REG) and wait for the timer to
> roll
> > over.  You will see T0IF (the interrupt request for TMR0) become set,
but
> > execution will not jump to address 4.  It will only jump to address 4 if
> > T0IF, T0IE and GIE are all set.
> >
> > Does this help?
> >
> > myke
> > ----- Original Message -----
> > From: "Michael A. Powers" <mapowers@IEEE.ORG>
> > To: <PICLIST@MITVMA.MIT.EDU>
> > Sent: Tuesday, August 27, 2002 10:24 PM
> > Subject: [PIC]: Interrupt Enable Flags - quick question
> >
> >
> > Let's say I set an interrupt enable bit to 0.  While the interrupt is
> > disabled, an event occurs which raises the interrupt flag.  Once the
> enable
> > bit is set to 1 (and the flag has not be reset), is the interrupt
called?
> >
> > Thanks.
> >
> > --
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> >
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>
>
>

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