Using Psoc to generate a pwm signal for a servo.

[RoboWanabe]

Hello can anyone please help me with generating a pwm signal for a servo using psoc? is it just the same as generating a signal for a motor? and any sujestions on frequencys to use?

Im trying to build a hovercraft and am now just stuck on the servos

Thank you.

 

[ronsimpson]

**broken link removed**

Often when someone asks this question we first need to know what motor (or servo) you are using. See above link.

 

[RoboWanabe]

ow sorry im using a HK15138 from hobbyking ill read you link now thanks

 

[RoboWanabe]

Thank you the link explains alot i think i just need to experiment abit with pulse width. i cant seem to find any data sheets on my servo telling me the correct pulsewidth for angle? or am i being stupid here?

 

[ronsimpson]

Yes you are using a servo. They want a pulse every 20mS (more or less). The pulse is in the range of 1.5mS and that timing sets the angel of the motor.

 

[RoboWanabe]

ok sorry i dnt no very much lol. how do you work the timeings out, if my PWM input frequency is 4khz my period can be between 0 to 256 and my pulse width can be between 0 and 256? any explanation on the workings of the frequency for PWM would be much appreciated. for example my understanding is---- the frequency input is 4khz so every0.00025s it pulses then the period divies that time up, say if i have a period of 256 it would divide it into pulse's at 14.625hz? am i on the right track with my knowledge?

Thank you for your help ron and sorry if i am confusing you, i tend to have that affect lol

 

[ronsimpson]

Usually the PWM is not used.
The hobby servos are intended to have a period of bout 20mS or 50hz. They do not run form 0 to 100%. They want a 1.25S to 2.75mS pulse. If you stop sending a pulse they turn off. More to read.

 

[RoboWanabe]

Thank you ron very helpfull

 

[Pommie]

I don't know what psoc is but as this is in this section I presume you will use a microcontroller. If so, I posted a thread about controlling servos. See clicky

Mike.