I just ordered and tried out some LS7083 & LS7084 encoder to counter
interface chips from the URL below and I am very pleased.  Much easier
than doing it the hard way with 74LS123's and gates.  The 83/84 is an
eight pin cmos dip that takes your quadrature encoder signals and gives
you a count up/count down or a pulse/direction to feed directly to your
PIC or a 74193 or a 4516 counter.  They also have a X1 / X4 option.  I
wish I had found these chips earlier.  If anyone knows of other encoder
chips (other than the HP), pls. post or email me.  They make working
with encoders easy.  BTW we use Intelligent Motion Systems stepper motor
drivers and would really like to find a servo motor controller that took
encoder inputs and pulse & direction control inputs.

http://www.usdigital.com/
http://www.usdigital.com/products/ls7083-84/
good luck

Mike Montaigne
Atomic Energy of Canada Ltd.
Station 18, Chalk River, Ontario
K0J 1J0, Canada

Phone (613) 584-3311 Ex. 4005
Fax:     (613) 584-4040
email:   montaignem@aecl.ca

> ----------
> From:         Sujay Sirur[SMTP:sirur@GIASBG01.VSNL.NET.IN]
> Sent:         Wednesday, May 06, 1998 1:43 PM
> To:   PICLIST@MITVMA.MIT.EDU
> Subject:      Re: Reading "bleeps" from incremental encoder
>
> Hi Franck,
>
> Your question has truly purplexed me. What are these "Bleeps"? I used
> to
> think that a shaft encoder gives 2 signals in quadrature (90 deg. out
> of
> phase). Both signals need to be used to know where the motor has moved
> to?
> Or are you doing speed control? If you are doing position control, I
> would
> suggest you use the HCTL2020 from HP. Its a rugged and proven design,
> might
> cost a bit though.
>
> At 16:56 5/4/98 -0400, Franck D Rougier wrote:
> >Hi,
> >
> >I am implementing a robot control circuit using the PIC16C73.  The
> motor is
> >driven by a National LMD18201 H-Bridge that is being fed from the
> >microcontroller with a PWM pulse train.
> >I successfully used the Timer2 (TMR2) in conjunction with the CCP1
> pin to
> >generate the pulse.
> >Now, I need to read "bleeps" or pulses from a digital encoder mounted
> on the
> >motor shaft.
> >I want to be able to count the number of bleeps from the encoder
> while the
> >pulse train is being generated by the pic, then shut the motor down.
> >I tried implementing on pin change interrupt from PORTB pin, so that
> each
> >time an interrupt occur, a counter is incremented. But when I
> debugged the
> >code, everything was working fine. That is the TMR2 will increment
> and set
> >CCP1 at the appropriate timing even if it is in the interrupt service
> >routine.  I built the circuit and nothing happened. Actually, the pic
> would
> >read a series of pulse from the encoder then turn off the pulse
> train. I
> >can't find the culprit!
> >
> >So my questions are:
> >
> >* how do I read the bleeps from the encoder (digital)?
> >* Does the TMR2 overflow interrupt is turned off when the code goes
> in the
> >ISR causing a o% duty cycle?
> >
> >Help me please.
> >
> >
> >Franck
> >
> >
> >PS: Please use the same subject for mail sorting purposes. Thank you.
> >
> >
> with best wishes and regards
> Sujay Sirur
>
> Email: sirur@giasbg01.vsnl.net.in
> Home: 604, Chitrapur Housing Society, Plot no 68, 15th Cross, 8th
> Main,
> Malleshwaram
>             Bangalore 560 055. INDIA   Tel. no: 91-80-344
>