On 9/14/05, Jinx <joecolquitt@clear.net.nz> wrote:
>=20
> > Now, does this mean that when I hit the button attached to RA3, the pic
> > should jump right to mem-location 0x04 and from there run my Interrupt
> > Service Routine?
>=20
> Is the button changing the level on RA3 ? IOW, is the button connecting
> RA3 to Vdd or, what is implied next, grounding a pull-up ?
>=20
> The /RAPU bit is cleared, which enables internal RA pull-ups
>=20
> ; Set prescaler to devide clock by 256
> MOVLW 0x07
> MOVWF OPTION_REG
>=20
> movlw b'00000111'
> ; 0 enable RA pull-ups
> ; 111 PS2,1,0 TMR0 pre-scaler =3D 256
> movwf option_reg
>=20
> You could also use Boolean bit-setting by name


There is an external pull-up in the switch circuit. I am sure that it=20
changes the port-state; I have used it before by polling RA3. The scematic=
=20
is in the PicKit1 manual.

Sean.
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