Hi Byron

    Thanks a lot for your advice
and explaination.I got it.
    I think I connect it to vdd(5V).

   Thanks again.

Chee Sze Keat

--- Byron A Jeff <byron@CC.GATECH.EDU> wrote: > >
> > Hello everyone
> >
> >     Sorry if this is a too simple
> > question.
>
> There are no simple questions... Ask away.
>
> >     I would like to know :
> > (1)It is is okay for to connect this
> >    mention pin 1 to Vdd(5V) for all
> >    the project?
>
> The PIC has a power on reset circuit internally. As
> long as +5 meets the
> required risetime. Here's the quote from Section
> 12.4 from the datasheet:
>
> A Power-on Reset pulse is generated on-chip when
> VDD rise is detected (in the range of 1.2V - 1.7V).
> To
> take advantage of the POR, tie the MCLR pin directly
> (or through a resistor) to VDD. This will eliminate
> exter-
> nal RC components usually needed to create a Power-
> on Reset. A maximum rise time for VDD is specified.
> See Electrical Specifications for details.
> When the device starts normal operation (exits the
> reset condition), device operating parameters
> (voltage,
> frequency, temperature,...) must be met to ensure
> oper-
> ation. If these conditions are not met, the device
> must
> be held in reset until the operating conditions are
> met.
> Brown-out Reset may be used to meet the start-up
> con-
> ditions. For additional information, refer to
> Application
> Note, AN007, "Power-up Trouble Shooting",
> (DS00007).
>
> The minimum listed risetime is 50 mV/ms. So the
> power supply must rise
> to 5V within 100 ms.
>
> >    Or should I connect it
> >    to a reset IC.
>
> Only if the power supply does not meet the risetime
> requirement.
>
> >Howver , I have a
> >    reset IC(monolithic ic pst600)
> >     with me,but I dont know the value
> >     the resistor and the capasitor that
> >     I should put.
>
> You need to make sure that the power is stable when
> the part is out of
> reset. But again unless you have an extremely slow
> rising power supply
> it's pretty much unecessary.
>
> BAJ
>
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>


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