how to change servo motor PWM

[dboy]

Hi,friends

Now I am researching servo motor with PIC BASC Pro. My problem is how to change servo motor PWM. I try to design programming. But it is not successful.Please give me some ideal. Thank you.

[Archangel]

pin var yourport.x ' for instance PortB.7
Duty var byte
cycle var byte

PWM pin,duty,cycle ' right out of the book
. . . . . . Or,
PWM PORTB.7,127,100 ' RIGHT FROM THE BOOK 50% duty cycle @ 100 cycles

Alter the values in the variables to change the values of the Duty time and Cycle time.
you can change them using digital methods or analog a/d converters and a potentiometer.

to alter numbers just . . . duty = 130
.................................. cycle = 150

[Acetronics2]

Hi, Joe

I think the question was " how to move the servo's arm" ...

Alain


DBoy,

As you have to learn everything about servos management ... I'd recommend you to make a Web search on R/C and Robotics sites about How a servo works.

Once that, with once more the SEARCH tool ,of this forum, now, you'll find how to do that with PicBasicPro...

Alain

[Archangel]

Hi, Joe

I think the question was " how to move the servo's arm" ...

Alain


DBoy,

As you have to learn everything about servos management ... I'd recommend you to make a Web search on R/C and Robotics sites about How a servo works.

Once that, with once more the SEARCH tool ,of this forum, now, you'll find how to do that with PicBasicPro...

Alain
Hi Alain,
Boy there a zillion open threads in here about that, I would be happy if I could just make interrupts work. :D

[Acetronics2]

Hi Alain,
I would be happy if I could just make interrupts work. :D

Could you PM me more about what you want to do ???

Alain

[dboy]

Thank you for your ideal. Actually servo motor pulse width variance from 1ms to 2 ms. I want servo motor shaft slowly turning. So I want to change PWM.

[Acetronics2]

Hi, Dboy

YOU know what you are doing ( or closer: trying to do ...)

WE do not know anything at all of you.


Here I'm wondering if you want to turm the servo arm slowly from a position to b position ... or if you want a continuous slow rotation of this arm ...

Solutions are not exactly ( way of speaking !!! lol ) the same ...

PLEASE

Explain what you want to do AS a FINAL GOAL ...

Alain

[dboy]

I want a continuous slow rotation of servo motor

[skimask]

I want a continuous slow rotation of servo motor

continuous slow rotation of a servo motor - Is this servo motor capable of continuous (like a clock) slow rotation? Most, if not all, R/C aircraft type servos have mechanical stops that won't allow them to rotate past a certain point. Unless you've modified a servo to do a slow rotation somehow (and I don't see that happening), this slow rotation isn't going to happen.

[mackrackit]

He could have one of these.
http://www.parallax.com/Store/Robots/RoboticComponents/tabid/198/CategoryID/57/List/0/Level/a/ProductID/102/Default.aspx?SortField=ProductName%2cProductName

[skimask]

He could have one of these.
http://www.parallax.com/Store/Robots/RoboticComponents/tabid/198/CategoryID/57/List/0/Level/a/ProductID/102/Default.aspx?SortField=ProductName%2cProductName

Not sure how it works...but I'm going to guess...
The servo's feedback pot is mechanically disconnected and locked into the 'center' position? Assume that this servo's center is 1.5ms. You give it a pulse of 1.6ms, it runs right at X speed. You give it a pulse of 1.7ms, it runs right at 2X speed. Same thing for the other direction? You give it a 1.4ms pulse, it runs left at X speed, pulse it at 1.3ms, and it runs left at 2X speed?
Therefore, the farther the input pulse is from 1.5ms, the faster it will travel in that particular direction?

[mackrackit]

Not sure how it works...but I'm going to guess...
The servo's feedback pot is mechanically disconnected and locked into the 'center' position? Assume that this servo's center is 1.5ms. You give it a pulse of 1.6ms, it runs right at X speed. You give it a pulse of 1.7ms, it runs right at 2X speed. Same thing for the other direction? You give it a 1.4ms pulse, it runs left at X speed, pulse it at 1.3ms, and it runs left at 2X speed?
Therefore, the farther the input pulse is from 1.5ms, the faster it will travel in that particular direction?
You got it. They used to sell these with instructions to modify, now they do the modification for you.
Makes really nice rolling gizmos.

[skimask]

You got it. They used to sell these with instructions to modify, now they do the modification for you.
Makes really nice rolling gizmos.

So, if you get a servo with a really tight deadband, it could be almost impossible to get the motor to stop 'cause it would always be trying to hit that sweet spot?

[mackrackit]

I have only used a dozen or so of these and have only had that problem a couple of times, but the little screw inside makes them adjustable. So it is not that big of a problem.

[skimask]

I have only used a dozen or so of these and have only had that problem a couple of times, but the little screw inside makes them adjustable. So it is not that big of a problem.

Well, that's a handy bit of information. I didn't know those types of servos were any sort of popular and/or used that much. That'll come in handy for a few things I've been wanting to mess with.

[rmteo]

Modifying R/C servos in the manner you described have been a fairly common way to get a low speed/low torque reversible motive system.