Thanks everyone for the help, I think I am going to
try and find a real scope that I can use and check
things out.

--- John Ferrell <johnferrell@EARTHLINK.NET> wrote:
> I just duplicated your set up with a 16F628, Futaba
> 9101 servo and 4 AA
> batteries as a power supply.
> The wave form was nice and square on a Tektronix
> 475A scope.
>
> The servo locked up nice & tight indicating all is
> working...
>
> Be certain that
>    Black is ground
>    Red is Vcc (center lead)
>    White is signal
>
> John Ferrell
> 6241 Phillippi Rd
> Julian NC 27283
> Phone: (336)685-9606
> johnferrell@earthlink.net
> Dixie Competition Products
> NSRCA 479 AMA 4190  W8CCW
> "My Competition is Not My Enemy"
>
> ----- Original Message -----
> From: "Joel Middleton" <chopsuey1973@YAHOO.COM>
> To: <PICLIST@MITVMA.MIT.EDU>
> Sent: Sunday, June 15, 2003 2:51 PM
> Subject: Re: [PIC]: Servo Pulse Problem
>
>
> > Futaba S3004
> > --- John Ferrell <johnferrell@EARTHLINK.NET>
> wrote:
> > > What kind of servo (brand/model).
> > > John Ferrell
> > > 6241 Phillippi Rd
> > > Julian NC 27283
> > > Phone: (336)685-9606
> > > johnferrell@earthlink.net
> > > Dixie Competition Products
> > > NSRCA 479 AMA 4190  W8CCW
> > > "My Competition is Not My Enemy"
> > >
> > > ----- Original Message -----
> > > From: "Joel Middleton" <chopsuey1973@YAHOO.COM>
> > > To: <PICLIST@MITVMA.MIT.EDU>
> > > Sent: Sunday, June 15, 2003 1:12 PM
> > > Subject: Re: [PIC]: Servo Pulse Problem
> > >
> > >
> > > > I found this schematic on the web and this is
> my
> > > exact
> > > > circuit except the servo signal is connected
> to
> > > pin 3
> > > > on portb. Also I have all the unused pins
> > > connected to
> > > > ground. Anyone see anything wrong with the
> > > circuit?
> > > >
> > > >
> > > > --- rneel@COX.NET wrote:
> > > > > I'm certainly no expert, but it looks like a
> > > classic
> > > > > capacitor discharge issue to me.  If you
> have a
> > > cap
> > > > > on this output, it will take time for it to
> > > > > discharge causing the slow decay in voltage
> > > instead
> > > > > of a nice sharp corner.  I can't see your
> > > circuit
> > > > > but do you have a cap connected across the
> pin
> > > you
> > > > > measured with the scope?
> > > > > >
> > > > > > From: Joel Middleton
> <chopsuey1973@YAHOO.COM>
> > > > > > Date: 2003/06/15 Sun AM 01:21:50 EDT
> > > > > > To: PICLIST@MITVMA.MIT.EDU
> > > > > > Subject: [PIC]: Servo Pulse Problem
> > > > > >
> > > > > > I believe I am having a problem with the
> pulse
> > > I
> > > > > am
> > > > > > sending to a servo connected directly to
> portb
> > > pin
> > > > > 3.
> > > > > > I have tmr0 set to overflow ever .0001
> > > seconds.
> > > > > The
> > > > > > variable 'count' is incremented each time
> tmr0
> > > > > > overflows when count reaches 200 it is
> reset
> > > to 0.
> > > > > > When count is equal to zero I set portb
> pin 3
> > > and
> > > > > when
> > > > > > count equals pw1 I clear the pin. I
> believe
> > > this
> > > > > > should give me a 1ms pulse every 20ms.
> This
> > > was
> > > > > not
> > > > > > working like I thought and I wanted to
> take a
> > > look
> > > > > at
> > > > > > the pulse so I downloaded one of those
> > > > > ocilloscopes
> > > > > > that runs through a sound card as I did
> not
> > > have
> > > > > > access to a real one. Well I found out
> that I
> > > am
> > > > > not
> > > > > > getting a nice square wave. The rising
> edge
> > > looks
> > > > > fine
> > > > > > but the falling edge is a slope. Can
> anyone
> > > tell
> > > > > me
> > > > > > how to correct this? I have included my
> code
> > > and
> > > > > also
> > > > > > attached an image I captured from the
> > > occiloscope.
> > > > > > Thanks.
> > > > > >
> > > > > >
> > > > > > LIST R=DEC
> > > > > >
> > > > > > INCLUDE "p16f84a.inc"
> > > > > >
> > > > > > CBLOCK 0x0C
> > > > > > _w
> > > > > > _status
> > > > > > _pclath
> > > > > > _fsr
> > > > > > count
> > > > > > pw1
> > > > > > ENDC
> > > > > >
> > > > > > __CONFIG _CP_OFF & _WDT_OFF & _XT_OSC &
> > > _PWRTE_ON
> > > > > >
> > > > > > push    macro
> > > > > >         movwf   _w
> ;Save
> > > > > registers
> > > > > >         movf    STATUS, w
> > > > > >         movwf   _status
> > > > > >         movf    PCLATH, w
> > > > > >         movwf   _pclath
> > > > > >         clrf    PCLATH
> > > > > >         endm
> > > > > >
> > > > > > pull    macro
> > > > > >         swapf   _pclath, w
> > > > > >         movwf   PCLATH
> > > > > >         movf    _status, w      ;Restore
> > > registers
> > > > > >         movwf   STATUS
> > > > > >         swapf   _w, f
> > > > > >         swapf   _w, w
> > > > > >         endm
> > > > > >
> > > > > > PAGE
> > > > > >
> > > > > >         org             0
> > > > > >         nop
> > > > > >
> > > > > >         goto    Main
> > > > > >
> > > > > >         org             4
> > > > > ;Interrupt
> > > > > >
> > > > > >         push
> > > > > >
> > > > > > Timer0
> > > > > >         btfss   INTCON, T0IF
> > > > > >                 goto    Iend
> > > > > >         movlw   165
> > > > > >         movwf   TMR0
> > > > > >         bcf             INTCON, T0IF
> > > > > >         incf    count
> > > > > >         movlw   200
> > > > > >         subwf   count, W
> > > > > >         btfss   STATUS, Z
> > > > > >                 goto    Step1
>
=== message truncated ===


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