How Servo Work

[koolguy]

Hello Guys,
I remember i had used Servo last 2 year back with PIC ADC to Servo with some forum member code.
I have this Servo with me
hxxp://robokits.co.in/motors/standard-dual-ball-bearing-servo
data sheet
I want to know how it work, there are 3 pulses of different width , it it will rotate at small angle the data sheet show 90 and 60 degree of movement if i want to move 20/30 degree
How to move it?

 

[kubeek]

Maybe instead of typing your questions here, try google next time. https://bfy.tw/2lpQ

 

[koolguy]

How did you made that Google Page?
Can't we rotates it at 45*?

 

[Ian Rogers]

Servo's need a certain pulse width... 1.5mS will put the servo at 90° 1.0mS will put the servo at 0° and 2mS will put it at 180°

So 45° will be 1.25mS

while
   turn on servo pin
   delay uS 1250
   turn off servo pin
   delay rest of cycle

 

[kubeek]

How did you made that Google Page?
Can't we rotates it at 45*?

lmgtfy.com
You can rotate it anything between 0° and 180°.

 

[koolguy]

So 45° will be 1.25mS
how to calculate ?

 

[kubeek]

So 45° will be 1.25mS
how to calculate ?

Are you serious?
Look at the numbers again.
1ms - 0°
1.5ms- 90°
2ms - 180°

And now the hard part, just like in kindergarten, how many ms do we need to get 45°?

 

[koolguy]

I forgot how to calculate i dnt remember school calculation.
something like : 1500/90 =16.7 ........

 

[Ian Rogers]

Simple algebra!!!!

(1000 /180) * 45° + 1000 = 1250....

 

[koolguy]

Simple algebra!!!!
(1000 /180) * 45° + 1000 = 1250....

i am not getting

 

[kubeek]

Then I really think you should consider gardening or some other simpler hobby, because electronics is clearly not for you. This is not some advanced mathemathics, this is third grade stuff.

 

[Ian Rogers]

How many micro seconds in one milli second.... 1000... You need to specify micro seconds for accuracy!!

If there are 180 degrees spread over 1 milli second you need to divide it by 180 to get the size ( in microseconds ) of each degree!!!!

Therefore 1000 uS / 180 degree = 5.5micro seconds..... 45 degrees will be 45 * 5.5 micro seconds... That equals 250 micro seconds... Then you have to add in the 1000 micro seconds that represent 0 degrees.. Voila 1250 micro seconds...

 

[koolguy]

This is not some advanced mathemathics, this is third grade stuff.

Is this true Electronics is to high.
i do it because i can earn more money with this subject.

 

[DerStrom8]

Is this true Electronics is to high.
i do it because i can earn more money with this subject.

You won't earn any money if you can't do it!

 

[koolguy]

You won't earn any money if you can't do it!

i am now rising linearly.

 

[koolguy]

How many micro seconds in one milli second.... 1000... You need to specify micro seconds for accuracy!!

If there are 180 degrees spread over 1 milli second you need to divide it by 180 to get the size ( in microseconds ) of each degree!!!!

Therefore 1000 uS / 180 degree = 5.5micro seconds..... 45 degrees will be 45 * 5.5 micro seconds... That equals 250 micro seconds... Then you have to add in the 1000 micro seconds that represent 0 degrees.. Voila 1250 micro seconds...

Can't we have less than 1* degree movement in servo

 

[koolguy]

How many micro seconds in one milli second.... 1000... You need to specify micro seconds for accuracy!!

If there are 180 degrees spread over 1 milli second you need to divide it by 180 to get the size ( in microseconds ) of each degree!!!!

Therefore 1000 uS / 180 degree = 5.5micro seconds..... 45 degrees will be 45 * 5.5 micro seconds... That equals 250 micro seconds... Then you have to add in the 1000 micro seconds that represent 0 degrees.. Voila 1250 micro seconds..

yes you are right​

Let see the Servo is at random position ........etc etc
i am thinking the internal circuit how it work i am not getting!

 

[DerStrom8]

i am now rising linearly.

Not from what I've seen.

 

[Ian Rogers]

In a cheap servo.... You'll be lucky to get ± 2°..

The other concern is there will be some noise.... Realistically you would need to use a hardware CCP to generate the PWM.... BUT!! there has to be an off time... most people use a 20hz pwm

EDIT*** Sorry I meant 200hz ( 5ms period )

 

[koolguy]

ok angular move depend on servo too.