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> Copyright 2003, Evolvian, Inc.
>
> Excerpt from original message:
> Robert,
>
> First, a major no-no ... although your method of coding could work, you should
> really, really, really (insert infinite loop here :-) use the definitions
> from the .inc files already created by Microchip.  They're part of the MPLAB
> package.  Otherwise, the code is difficult to read, and adds major sources of
> errors.  Especially if, as you say, you're a programmer. :-)
>
> That said, assuming your code compiles okay and does have the correct register
> addresses, if the switch were in it's unpressed state, RA1 would be "1".  The
> code would loop at BEGIN and the line after that (goto BEGIN).  Now, if the
> switch were pressed, RA0 goes to "0", so the code sets PORTB to all "1"'s
> which would turn on the LED, BUT...assuming the switch "bounces", as is
> expected, RA1 would flicker between "1" and "0" for a short time.  But long
> enough that as it gets to KEEPON, RA1 could be at 0 and would not loop at
> KEEPON.  It would go straight to clearing portB and exit.  It could also loop
> at KEEPON a few times before exiting due to the same switch bounce problem.
> A few times is very fast, since the internal oscillator is 4Mhz, so you would
> not even see the LED come on.
>
> Quick test... try a really large capacitor at the input to RA1 (Cap +ve to
> RA1, cap -ve to gnd).  If that solves your problem then you know it's the
> bounce issue.
>
> Cheers,
> -Neil
>
> On Tuesday 10 June 2003 19:47, rrc124+@PITT.EDU scribbled:
> > I can't get my inputs to work. I am using a pull up switch, have set all
> > pins but 1 to outputs, then tied them to ground. I am using a PIC16F628
> > with the configs set to everything off/disabled except the power up timer.
> > I have selected the internal oscillator. I'm a programmer..not EE, so
> > that's my weak point but i have been checking the circuit for 3 days and
> > can't find what's wrong. The chip works because i got one of those LED
> > blinking things to work fine. Guys...thank you so much...it's very
> > upsetting when you're just starting out and can't get the easiest thing to
> > work. The only odd thing i could find was that my programming software
> > (WinPicProg, from Dontronics) generates a different config word then does
> > MPLAB with the same settings.
> >
> > Here is my code:
> >
> > TMR0            EQU             1
> > OPTION_R        EQU             1
> > PORTA           EQU             5
> > PORTB           EQU             6
> > TRISA           EQU             5
> > TRISB           EQU             6
> > STATUS          EQU             3
> > ZEROBIT         EQU             2
> > CARRY           EQU             0
> > PCON            EQU             0EH
> > COUNT           EQU             20H
> >
> >                         LIST P=16F628
> >           ;  tells which processor is use ;MPLAB generated        __CONFIG
> > 0x3F10
> >                         __CONFIG 0x3D10  ;WinPicProg generated
> >
> >                         org             0
> >                         goto    START
> >
> > ; config section
> >
> > START                   bsf     STATUS, 5
> >                         movlw   b'11111111'
> >                         movwf   TRISA
> >                         movlw   b'00000000'
> >                         movwf   TRISB
> >
> >                         movlw   b'00000100'
> >                         movwf   OPTION_R
> >                         clrf    PCON
> >
> >                         bcf     STATUS, 5
> >                         clrf    PORTA
> >                         clrf    PORTB
> >
> > ; program starts now
> >
> > BEGIN           btfsc   PORTA, 1
> >                         goto    BEGIN
> >                         movlw   b'11111111'
> >                         movwf   PORTB
> > KEEPON          btfss   PORTA, 1
> >                         goto    KEEPON
> >                         clrf    PORTB
> >                         goto    BEGIN
> >
> >                         END
> >
> > Here is my circuit:
> >                                    GND
> >
> > [9V+ Battery]--[914 diode]--[7805 Volt Reg]--+
> >
> >                           +-----[10k Res]----+
> >
> >             A1/PIN 18-----+--[switch]--GND   |
> >
> >            Vdd/PIN 14------------------------+
> >
> >            Vss/PIN 05------------------------GND
> >
> >             B4/PIN 10--[470 Ohm Res]--[LED]--GND
> >
> >             B3/PIN 09--[470 Ohm Res]--[LED]--GND
> >
> > All other pins set as output, tied to ground. The switch part of the
> > circuit allows 4.5V to A1 and when pressed drops the voltage down to 0. I
> > checked with my multimeter. Thank you so much everyone.
> >
> > E-Mail: rrc124@pitt.edu
> >
> > Robert Campbell
>
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--
Happy Trails....  Larry

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