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'Servo Code Not Working'
1997\12\21@141614 by Jean-Francois Joly

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part 0 755 bytes content-type:application/x-unknown-content-type-asm_auto_file;I'v been modifying Peter Baine's servo controller code so I could
control a single servo on a pic16c84 running at 4 MHz. (I wanted it to
be as simple as possible) But for some reason, it doesn't work. All the
servo does is that it points in a certain direction and stays there.
Even if I change the delay for the pulse duration the servo won't move a
bit.

Could someone take a little look at the program and see if something's
missing? Attached to this message is the small program.

Thank you very much,
Jean-Francois Joly


Content-Type: application/x-unknown-content-type-asm_auto_file;
name="srvctrl2.asm"
Content-Disposition: inline; filename="srvctrl2.asm"

Attachment converted: wonderland:srvctrl2.asm (????/----) (0000E6F0)

1997\12\22@032402 by Peter Baines

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Hi Jean,
       I have had a quick look at your modified version of my code. You seem to
have misunderstood the timing requirements of the servos. Each servo you
want to control must have a pulse of between 1 and 2 ms with a duty cycle
of 18 to 20 ms. your duty cycle timer must take account of the duration of
the control pulse. I.E. after the counter for the pulse has expired you
must also add the rest of the 2ms wait before entering the duty cycle
timer. If you like I will Modify the code and post it back to you.

Cheers Peter Baines.....

====================================
Remember .... Every Silver Lining
Has It's Cloud
====================================

----------
: From: Jean-Francois Joly <spam_OUTjolyalTakeThisOuTspamCAPITALNET.COM>
: To: .....PICLISTKILLspamspam@spam@MITVMA.MIT.EDU
: Subject: Servo Code Not Working
: Date: Sunday, December 21, 1997 7:05 PM
:
: Hello everyone,
:
: I'v been modifying Peter Baine's servo controller code so I could
: control a single servo on a pic16c84 running at 4 MHz. (I wanted it to
: be as simple as possible) But for some reason, it doesn't work. All the
: servo does is that it points in a certain direction and stays there.
: Even if I change the delay for the pulse duration the servo won't move a
: bit.
:
: Could someone take a little look at the program and see if something's
: missing? Attached to this message is the small program.
:
: Thank you very much,
: Jean-Francois Joly
:
:

1997\12\22@033848 by Peter Baines

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part 0 891 bytes content-type:application/octet-stream; name="srvctrl2.asm"Peter ..........

====================================
Remember .... Every Silver Lining
Has It's Cloud
====================================
:
: I'v been modifying Peter Baine's servo controller code so I could
: control a single servo on a pic16c84 running at 4 MHz. (I wanted it to
: be as simple as possible) But for some reason, it doesn't work. All the
: servo does is that it points in a certain direction and stays there.
: Even if I change the delay for the pulse duration the servo won't move a
: bit.
:
: Could someone take a little look at the program and see if something's
: missing? Attached to this message is the small program.
:

Content-Type: application/octet-stream; name="srvctrl2.asm"
Content-Description: srvctrl2.asm ()
Content-Disposition: attachment; filename="srvctrl2.asm"

Attachment converted: wonderland:srvctrl2.asm (????/----) (0000E753)

1997\12\22@182524 by johnb

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Someone wrote:
> Each servo you want to control must have a pulse of between 1 and 2 ms with a
duty
> cycle of 18 to 20 ms. Your duty cycle timer must take account of the duration
of
> the control pulse. I.E. after the counter for the pulse has expired you must
also add
> the rest of the 2ms wait before entering the duty cycle timer.

In my experience the repetition frequency is of little importance when
testing servos. I have used, for some years, a program that pulses a pin
on the Centronics port of a PC for such tests. This repeats at the
"timer-tick" interrupt rate, which is 18.6 ticks/sec, or a 54 mSec
period. This is a perfectly adequate arrangement. You can speed up the
timer-tick if you want to.

The idea is to write a small TSR, to which the timer-tick interrupt is
redirected 18.6 times per second. The TSR generates the 1-2 msec pulse.
It gets its pulse-width data from a Basic or other program which runs in
the normal way; this program takes its input from the keyboard, and
passes it to the TSR.

In fact, instead of connecting a servo to the Centronics port, why not
connect the transmitter output stage to it, and use the PC as the
transmitter? Then you can program it in Basic. It's a bit bulky to carry
around of course, especially as you also need a Honda motor-generator to
power it all with.

John Blackburn.

1997\12\22@204505 by Eric Naus
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Hi,

I have uploaded code on my website that controls 7 servos and is written
for the 16c84. It can be improved but it does work as stands. If you are
interested.
Just go into Robotic Projects

http://webhome.idirect.com/~bine

Bye for Now

Eric
At 08:23 AM 12/22/97 -0000, you wrote:
>Hi Jean,
>        I have had a quick look at your modified version of my code. You
seem to
{Quote hidden}

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