you can have a PWM output with a duty cycle that is fed from a
variable.
Say you have 2 switches.
Switch A will result in X=X+1
Switch B will result in X=X-1
Of course you need a delay so that switch does not hit (or pass) the
maximum in a few seconds.
Of course you also need a to check that X is never less than zero and
never higher than your max duty cycle for the PWM, or whatever you
are trying to do.
My 15 year old son wrote this note. He had programmed his BOEBOT to
speed up and slow down, but has now lost the code in a computer
crash. Was it PWM? He seems to recall RAMP, but that doesnt appear
to be it. Thanks for the help.
--- In basicstamps@yahoogroups.com, "surbahars" <kingfm@y...> wrote:
> My 15 year old son wrote this note. He had programmed his BOEBOT
to
> speed up and slow down, but has now lost the code in a computer
> crash. Was it PWM? He seems to recall RAMP, but that doesnt
appear
> to be it. Thanks for the help.
Thanks for the additional information.
What would make it speed up or slow down ?
If there was a sensor so that as the sensor approached a wall or
chair, that could make it slow down.
or there might be some other way to start the ramp.
We are more than willing to offer some help to figure out what is
needed.
PWM is "pulse width modulation" and is a method to control the amount of
energy to a load.
More specifically in your case. Many people I have talked to have a
misunderstanding of TRUE PWM. With PWM, the frequency of the output pulse does
not
change, but the length of the pulse varies.
For me this is hard to explain in writing, see these links.
In this first link, and assuming the pulse being high causes current to go
through your load (motor) then the motor will run almost at full speed.
Back to the first link, if the width of the duty is 50% of the width of the
period, the motor will run at 1/2 speed (it receives 1/2 total available
energy).
There are other nuances to consider such as the type of load or motor and the
actual period, but in a nut shell, this should help you better understand PWM.
Ramp would refer to changing the PWM to make the motor start out at one speed
and end up at a different speed....ie, ramping up or down by increasing or
decreasing the PWM duty.
ken
My 15 year old son wrote this note. He had programmed his BOEBOT to
speed up and slow down, but has now lost the code in a computer
crash. Was it PWM? He seems to recall RAMP, but that doesnt appear
to be it. Thanks for the help.
[noparse][[/noparse]Non-text portions of this message have been removed]
'Halt' is:
PULSOUT LeftPin, 750
PULSOUT RightPin, 750
I believe you can 'ramp' between
the 750 to 1000, and 750 to 500, to get a
gradual increase in speed -- but I havn't
done it myself (yet).
--- In basicstamps@yahoogroups.com, smartdim@a... wrote:
> PWM is "pulse width modulation" and is a method to control the
amount of
> energy to a load.
>
> More specifically in your case. Many people I have talked to have a
> misunderstanding of TRUE PWM. With PWM, the frequency of the output
pulse does not
> change, but the length of the pulse varies.
>
> For me this is hard to explain in writing, see these links.
>
> In this first link, and assuming the pulse being high causes
current to go
> through your load (motor) then the motor will run almost at full
speed.
>
> http://www.ee.nmt.edu/~rison/ee308_spr00/supp/000301/pwm.gif
>
> In this next link, with same assumption of a high pulse causes
current
> through the load, the motor will run slower compared to the first
link.
>
> http://sise.ttu.ee/mechatronics/mhk/materjalid/mhk5300/juhendid/pwmsig
naal.jpg
>
>
> Back to the first link, if the width of the duty is 50% of the
width of the
> period, the motor will run at 1/2 speed (it receives 1/2 total
available
> energy).
>
> There are other nuances to consider such as the type of load or
motor and the
> actual period, but in a nut shell, this should help you better
understand PWM.
>
> Ramp would refer to changing the PWM to make the motor start out at
one speed
> and end up at a different speed....ie, ramping up or down by
increasing or
> decreasing the PWM duty.
>
> ken
>
> My 15 year old son wrote this note. He had programmed his BOEBOT
to
> speed up and slow down, but has now lost the code in a computer
> crash. Was it PWM? He seems to recall RAMP, but that doesnt
appear
> to be it. Thanks for the help.
>
>
> [noparse][[/noparse]Non-text portions of this message have been removed]
Archiver
Posts: 46,084
Comments
wrote:
> how do you ramp??
need more data.
What are you ramping ?
you can have a PWM output with a duty cycle that is fed from a
variable.
Say you have 2 switches.
Switch A will result in X=X+1
Switch B will result in X=X-1
Of course you need a delay so that switch does not hit (or pass) the
maximum in a few seconds.
Of course you also need a to check that X is never less than zero and
never higher than your max duty cycle for the PWM, or whatever you
are trying to do.
Then your duty cycle can be X
Dave
=====================================
how do you ramp??
[noparse][[/noparse]Non-text portions of this message have been removed]
smartdim@a... writes:
> What do you mean by ramping?
>
Ramping up is slowly increasing the current or voltage or speed or whatever.
Ramping down is decreasing the same.
Sid
[noparse][[/noparse]Non-text portions of this message have been removed]
iterations of ramping.
Obviously, you can have a voltage ramp when viewed on a scope looks like a
triangle wave.
Or as you said, a speed ramp, increasing or decreasing the angulary velocity
of a motor.
=============
Ramping up is slowly increasing the current or voltage or speed or whatever.
Ramping down is decreasing the same.
Sid
[noparse][[/noparse]Non-text portions of this message have been removed]
speed up and slow down, but has now lost the code in a computer
crash. Was it PWM? He seems to recall RAMP, but that doesnt appear
to be it. Thanks for the help.
> My 15 year old son wrote this note. He had programmed his BOEBOT
to
> speed up and slow down, but has now lost the code in a computer
> crash. Was it PWM? He seems to recall RAMP, but that doesnt
appear
> to be it. Thanks for the help.
Thanks for the additional information.
What would make it speed up or slow down ?
If there was a sensor so that as the sensor approached a wall or
chair, that could make it slow down.
or there might be some other way to start the ramp.
We are more than willing to offer some help to figure out what is
needed.
Dave
energy to a load.
More specifically in your case. Many people I have talked to have a
misunderstanding of TRUE PWM. With PWM, the frequency of the output pulse does
not
change, but the length of the pulse varies.
For me this is hard to explain in writing, see these links.
In this first link, and assuming the pulse being high causes current to go
through your load (motor) then the motor will run almost at full speed.
http://www.ee.nmt.edu/~rison/ee308_spr00/supp/000301/pwm.gif
In this next link, with same assumption of a high pulse causes current
through the load, the motor will run slower compared to the first link.
http://sise.ttu.ee/mechatronics/mhk/materjalid/mhk5300/juhendid/pwmsignaal.jpg
Back to the first link, if the width of the duty is 50% of the width of the
period, the motor will run at 1/2 speed (it receives 1/2 total available
energy).
There are other nuances to consider such as the type of load or motor and the
actual period, but in a nut shell, this should help you better understand PWM.
Ramp would refer to changing the PWM to make the motor start out at one speed
and end up at a different speed....ie, ramping up or down by increasing or
decreasing the PWM duty.
ken
My 15 year old son wrote this note. He had programmed his BOEBOT to
speed up and slow down, but has now lost the code in a computer
crash. Was it PWM? He seems to recall RAMP, but that doesnt appear
to be it. Thanks for the help.
[noparse][[/noparse]Non-text portions of this message have been removed]
by a Servo based motor for each wheel.
This goes full speed in one direction by:
DoMotor:
PULSOUT LeftPin, 1000
PULSOUT RightPin, 500
PAUSE 20
GOTO DoMotor
'Halt' is:
PULSOUT LeftPin, 750
PULSOUT RightPin, 750
I believe you can 'ramp' between
the 750 to 1000, and 750 to 500, to get a
gradual increase in speed -- but I havn't
done it myself (yet).
--- In basicstamps@yahoogroups.com, smartdim@a... wrote:
> PWM is "pulse width modulation" and is a method to control the
amount of
> energy to a load.
>
> More specifically in your case. Many people I have talked to have a
> misunderstanding of TRUE PWM. With PWM, the frequency of the output
pulse does not
> change, but the length of the pulse varies.
>
> For me this is hard to explain in writing, see these links.
>
> In this first link, and assuming the pulse being high causes
current to go
> through your load (motor) then the motor will run almost at full
speed.
>
> http://www.ee.nmt.edu/~rison/ee308_spr00/supp/000301/pwm.gif
>
> In this next link, with same assumption of a high pulse causes
current
> through the load, the motor will run slower compared to the first
link.
>
>
http://sise.ttu.ee/mechatronics/mhk/materjalid/mhk5300/juhendid/pwmsig
naal.jpg
>
>
> Back to the first link, if the width of the duty is 50% of the
width of the
> period, the motor will run at 1/2 speed (it receives 1/2 total
available
> energy).
>
> There are other nuances to consider such as the type of load or
motor and the
> actual period, but in a nut shell, this should help you better
understand PWM.
>
> Ramp would refer to changing the PWM to make the motor start out at
one speed
> and end up at a different speed....ie, ramping up or down by
increasing or
> decreasing the PWM duty.
>
> ken
>
> My 15 year old son wrote this note. He had programmed his BOEBOT
to
> speed up and slow down, but has now lost the code in a computer
> crash. Was it PWM? He seems to recall RAMP, but that doesnt
appear
> to be it. Thanks for the help.
>
>
> [noparse][[/noparse]Non-text portions of this message have been removed]
Ramp what?
-- Jon Williams
-- Applications Engineer, Parallax
-- Dallas Office
Original Message
From: lexcube2002 [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=TBYY1ctA5XH6jbGuqxAgFL7M7OhuJaFv6YJEYvi2a7jsebJ9LRp3F8OGdh97Hdkln7tWF5ntekw75qXFkIlW]lexcube2002@y...[/url
Sent: Friday, April 23, 2004 11:38 PM
To: basicstamps@yahoogroups.com
Subject: [noparse][[/noparse]basicstamps] ramping
how do you ramp??