Trying to get al williams pwm chip to go
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Hi Bill.
I know you've mentioned the Diverse controller to me before, but I don't
know much about it myself. Are you sure the motors you are using are going
to respond to PWM?
Since the motors are reacting to the PWM, it sounds like you have the chip
working (can you see the output on a scope, or modulate an LED to see if it
working?). However, it sounds like either the motors are not amenable to PWM
at the frequency generated or the connection to the controller is not
correct.
I will tell you that many motors will not run at very low PWM values because
you never generate enough average voltage to overcome the motor's initial
inertia (this is like trying to start your car in 4th gear). The symptom is
that you can run the motor at high speeds and decrease to a low speed
(because the inertia's sign is in the right direction) but you can't run it
at the low speed from a cold stop. This isn't a PAK problem but a physics
problem.
One thing that would be easy to try is to drive the controller from the
Stamp's PWM command. If that works, then you have some sort of PAK problem
(bad PAK, bad commands, bad wiring). If it doesn't work, the problem is not
in the PAK. The controller may not be wired to the PWM source properly, for
example. I would use a small DC motor from Radio Shack and see if I could
drive that with either the Stamp or PAK. If I couldn't then again the
problem is the controller. If I can, there is an issue with the motor.
DC motors can be brush, brushless, or inductive. Each have their own issues.
Again, a scope could really tell the story by looking at the waveform at the
motor terminals.
Let me know if any of that sheds some light.
Regards,
Al Williams
AWC
http://www.al-williams.com/awce
>
Original Message
> From: Bill Katakis [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=cEmonXvoO_w_MvKqNb3KAtZCxWeoSuzt3HRFJRhc8V3MWWC6IKFPKSCFlsh0EV8WR1rStev61Krx7uX470WAZTyR]bkatakis@m...[/url
> Sent: Sunday, November 12, 2000 2:37 PM
> To: BASIC STAMP MAILING LIST DO NOT CC
> Subject: [noparse][[/noparse]basicstamps] TRYING TO GET AL WILLIAMS PWM CHIP TO GO
>
>
> Hi,
>
> I'm trying to get an Al Williams pak5a pwm chip to run 3 30amp 12vdc
> motor controllers from http://divelec.tripod.com/ (Deverse
> Electornics). I can get the stamp
> to enable the controllers and set the motor direction which causes the
> relays to snap,, but when I send pwm from the pak5a all I get is a
> growling sound from the motor with no shaft rotation. The motors are
> Motorguide 30 and 35 pound thrust trolling motors,, the kind used for
> fishing. Any ideas about what I may be doing wrong? This is the
> second pak5a I've tried, and I have taken pains to be very aware of the
> static sensitive nature of this second chip. When I get this project
> working I'm going to make the hardware, schematics, and code available
> for free on my website. Its using an at keyboard and an Al Williams
> pak6 to provide unique realtime rs232 variables to the stamp, which then
> sends them on a long wire to a second stamp,(via rs232/485/fiber/or
> etc.) which then controls the motors speed, and direction in 3 axis.
> Help!
> Bill Katakis
> bkatakis@m...
>
>
>
>
I know you've mentioned the Diverse controller to me before, but I don't
know much about it myself. Are you sure the motors you are using are going
to respond to PWM?
Since the motors are reacting to the PWM, it sounds like you have the chip
working (can you see the output on a scope, or modulate an LED to see if it
working?). However, it sounds like either the motors are not amenable to PWM
at the frequency generated or the connection to the controller is not
correct.
I will tell you that many motors will not run at very low PWM values because
you never generate enough average voltage to overcome the motor's initial
inertia (this is like trying to start your car in 4th gear). The symptom is
that you can run the motor at high speeds and decrease to a low speed
(because the inertia's sign is in the right direction) but you can't run it
at the low speed from a cold stop. This isn't a PAK problem but a physics
problem.
One thing that would be easy to try is to drive the controller from the
Stamp's PWM command. If that works, then you have some sort of PAK problem
(bad PAK, bad commands, bad wiring). If it doesn't work, the problem is not
in the PAK. The controller may not be wired to the PWM source properly, for
example. I would use a small DC motor from Radio Shack and see if I could
drive that with either the Stamp or PAK. If I couldn't then again the
problem is the controller. If I can, there is an issue with the motor.
DC motors can be brush, brushless, or inductive. Each have their own issues.
Again, a scope could really tell the story by looking at the waveform at the
motor terminals.
Let me know if any of that sheds some light.
Regards,
Al Williams
AWC
http://www.al-williams.com/awce
>
Original Message
> From: Bill Katakis [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=cEmonXvoO_w_MvKqNb3KAtZCxWeoSuzt3HRFJRhc8V3MWWC6IKFPKSCFlsh0EV8WR1rStev61Krx7uX470WAZTyR]bkatakis@m...[/url
> Sent: Sunday, November 12, 2000 2:37 PM
> To: BASIC STAMP MAILING LIST DO NOT CC
> Subject: [noparse][[/noparse]basicstamps] TRYING TO GET AL WILLIAMS PWM CHIP TO GO
>
>
> Hi,
>
> I'm trying to get an Al Williams pak5a pwm chip to run 3 30amp 12vdc
> motor controllers from http://divelec.tripod.com/ (Deverse
> Electornics). I can get the stamp
> to enable the controllers and set the motor direction which causes the
> relays to snap,, but when I send pwm from the pak5a all I get is a
> growling sound from the motor with no shaft rotation. The motors are
> Motorguide 30 and 35 pound thrust trolling motors,, the kind used for
> fishing. Any ideas about what I may be doing wrong? This is the
> second pak5a I've tried, and I have taken pains to be very aware of the
> static sensitive nature of this second chip. When I get this project
> working I'm going to make the hardware, schematics, and code available
> for free on my website. Its using an at keyboard and an Al Williams
> pak6 to provide unique realtime rs232 variables to the stamp, which then
> sends them on a long wire to a second stamp,(via rs232/485/fiber/or
> etc.) which then controls the motors speed, and direction in 3 axis.
> Help!
> Bill Katakis
> bkatakis@m...
>
>
>
>
Comments
chips. 30A inductive loads can be tricky.
Consider trying to drive small motors or even a small bulb to narrow
in on whether it is a problem with Al's chips or your motor driver,
motor supply or poor ground isolation.
Peter H. Anderson, http://www.phanderson.com/stamp/
Homebrew BS2, Basic Stamp Starter Packages
--- In basicstamps@egroups.com, Bill Katakis <bkatakis@m...> wrote:
> Hi,
>
> I'm trying to get an Al Williams pak5a pwm chip to run 3 30amp 12vdc
> motor controllers from http://divelec.tripod.com/ (Deverse
> Electornics). I can get the stamp
> to enable the controllers and set the motor direction which causes
the
> relays to snap,, but when I send pwm from the pak5a all I get is a
> growling sound from the motor with no shaft rotation. The motors
are
>Hi,
>
>I'm trying to get an Al Williams pak5a pwm chip to run 3 30amp 12vdc
>motor controllers from http://divelec.tripod.com/ (Deverse
>Electornics). I can get the stamp
>to enable the controllers and set the motor direction which causes the
>relays to snap,, but when I send pwm from the pak5a all I get is a
>growling sound from the motor with no shaft rotation. The motors are
>Motorguide 30 and 35 pound thrust trolling motors,, the kind used for
>fishing. Any ideas about what I may be doing wrong? This is the
>second pak5a I've tried, and I have taken pains to be very aware of the
>static sensitive nature of this second chip. When I get this project
>working I'm going to make the hardware, schematics, and code available
>for free on my website. Its using an at keyboard and an Al Williams
>pak6 to provide unique realtime rs232 variables to the stamp, which then
>sends them on a long wire to a second stamp,(via rs232/485/fiber/or
>etc.) which then controls the motors speed, and direction in 3 axis.
>Help!
>Bill Katakis
>bkatakis@m...
Hi Bill -
Skip the motors for a moment, and do a simple systems check. Try using a 2 x 12
volt light bulbs (automotive tail light bulbs or similar) in series, and see if
dimming occurs. Prof. Anderson said a mouthful, when he said "30A inductive
loads can be tricky".
The light bulbs will provide a heavy load, but with any concerns of
interference. Thus if connections are loose, the board can't take the load, the
batteries are low, or any other condition is present, the light bulbs will
probably BE dim and STAY DIM. If they react as an ordinary dimmer would, you
have then "scoped out" the basic system without a 'scope !
Al's O'scope idea is perfect, but not all of us have one handy.
Maybe that's on the horizon for the next round of pocket-ware !
Hope this provides SOME answers, so the debugging effort can proceed from there.
Regards,
Bruce Bates
I'm trying to get an Al Williams pak5a pwm chip to run 3 30amp 12vdc
motor controllers from http://divelec.tripod.com/ (Deverse
Electornics). I can get the stamp
to enable the controllers and set the motor direction which causes the
relays to snap,, but when I send pwm from the pak5a all I get is a
growling sound from the motor with no shaft rotation. The motors are
Motorguide 30 and 35 pound thrust trolling motors,, the kind used for
fishing. Any ideas about what I may be doing wrong? This is the
second pak5a I've tried, and I have taken pains to be very aware of the
static sensitive nature of this second chip. When I get this project
working I'm going to make the hardware, schematics, and code available
for free on my website. Its using an at keyboard and an Al Williams
pak6 to provide unique realtime rs232 variables to the stamp, which then
sends them on a long wire to a second stamp,(via rs232/485/fiber/or
etc.) which then controls the motors speed, and direction in 3 axis.
Help!
Bill Katakis
bkatakis@m...
controllers are working correctly - my experience is that when a motor just
growls it is not getting enough current (excluding ac motors for this
discussion)
if you just give the motors 12 from car battery will they spin correctly ?
I dont know what your relays are doing to set the direction - are these PM
motors or are you switching fields ?
simulate the stamp - get everything to work - then use stamp
richard
Original Message
From: "Bill Katakis" <bkatakis@m...>
To: "BASIC STAMP MAILING LIST DO NOT CC" <basicstamps@egroups.com>
Sent: Sunday, November 12, 2000 2:37 PM
Subject: [noparse][[/noparse]basicstamps] TRYING TO GET AL WILLIAMS PWM CHIP TO GO
> Hi,
>
> I'm trying to get an Al Williams pak5a pwm chip to run 3 30amp 12vdc
> motor controllers from http://divelec.tripod.com/ (Deverse
> Electornics). I can get the stamp
> to enable the controllers and set the motor direction which causes the
> relays to snap,, but when I send pwm from the pak5a all I get is a
> growling sound from the motor with no shaft rotation. The motors are
> Motorguide 30 and 35 pound thrust trolling motors,, the kind used for
> fishing. Any ideas about what I may be doing wrong? This is the
> second pak5a I've tried, and I have taken pains to be very aware of the
> static sensitive nature of this second chip. When I get this project
> working I'm going to make the hardware, schematics, and code available
> for free on my website. Its using an at keyboard and an Al Williams
> pak6 to provide unique realtime rs232 variables to the stamp, which then
> sends them on a long wire to a second stamp,(via rs232/485/fiber/or
> etc.) which then controls the motors speed, and direction in 3 axis.
> Help!
> Bill Katakis
> bkatakis@m...
>
>
>
>
>