Hi Sai,

You need to maintain similar logic to this (need to wait variable time for
duty cycle and you should not worry about how many cycles you are doing
this -- you need to maintain servo pulses all times anyway, so it is better
just limiting movements). BTW: You also can have one potmeter to active
speed and direction: if you have a number from 0..1023 then subtract 512
from it and you will get +-512 so the upper half position will cause servo
go upwards, lower position to go downwards...

Anyway, here is the pseudo code with the button + potmeter version:

// loop forever
while (1) {
    // put your potmeter acquisition here
    ....


    // change servo position by speed and direction
    if ( GPIO & (1<<3) ) {
        pw +=3D quotient );
    }
    else {
        pw -=3D quotient );
    }

    // limit servo movements
    if ( pw < 1000 ) {
        pw =3D 1000;
    }
    if ( pw > 2000 ) {
        pw =3D 2000;
    }

    // wait for variable time
    for ( i =3D pw; i > 0; i-- ) {
        __delay_us(1);
    }
    __delay_ms(18);
}

Tamas



On 15 February 2012 02:55, yamanoor sairam <yamanoorsai@yahoo.com> wrote:

> Hello All,
>
> I guess this is my third mail on the same topic. I am trying to control a
> servo motor using PIC 12F675. I was successful in driving the servo as we=
ll
> as achieving the speed control for the servo. Thanks for the help from th=
e
> members of this list.
>
> Now, my speed control is quite flaky. I tried tweaking my code here and
> there but I have had no success so far.
>
> My main objective is that the servo should spin 0 to 90 and back based on
> the data from toggle switch. I achieved this goal. When I turn a
> potentiometer, the speed at which the servo rotates should change. I
> achieved this too. However, the servo is not rotating 90 degrees at all t=
he
> time.
>
> It rotates 90 ish -120 degrees at high speeds and rotates only 30-45
> degrees on low speeds (or some weird behavior is happening). I want my
> servo to rotate 90 degrees but just my speed should vary.
>
> Can any one point me to the error in my code?
>
> All this code is inside a while loop.
>
> GO_DONE=3D1;
> while(GO_DONE);
> V_in=3D(ADRESH<<8)|ADRESL;
> quotient=3DV_in/200; // I am dividing this because I will have integers
> between 1 to 5
> if(quotient<=3D1)
> {
> quotient=3D1;
> }
> if(GPIO&(1<<3))
> {
> while(counter>1000)
> {
>  counter=3Dcounter-(20*quotient);
> GPIO|=3D(1<<2);
>  cnt_1=3Dcounter;
>  while(cnt_1>0)
>  {
> __delay_us(1);
>  cnt_1--;
> }
> GPIO&=3D~(1<<2);
> __delay_ms(18);
> }
> cnt=3D1000;//reset of counter for reverse direction
> }
> elseif(!(GPIO&(1<<3)))
> {
> while(cnt<1500)
> {
> cnt=3Dcnt+(20*quotient);
> GPIO|=3D(1<<2);
> cnt_2=3Dcnt;
> while(cnt_2>0)
> {
> __delay_us(1);
> cnt_2--;
> }
> GPIO&=3D~(1<<2);
> __delay_ms(18);
> }
> counter=3D1500;//reset of counter for forward direction
> }
> }
>
>
> Any help is appreciated
>
> Sai
> }
>
> --
> http://www.piclist.com PIC/SX FAQ & list archive
> View/change your membership options at
> http://mailman.mit.edu/mailman/listinfo/piclist
>



--=20
int main() { char *a,*s,*q; printf(s=3D"int main() { char *a,*s,*q;
printf(s=3D%s%s%s, q=3D%s%s%s%s,s,q,q,a=3D%s%s%s%s,q,q,q,a,a,q); }",
q=3D"\"",s,q,q,a=3D"\\",q,q,q,a,a,q); }
--=20
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
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.