C36R servo motor

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C36R servo motor

Postby picpicpikapika » Thu Feb 10, 2011 7:12 pm

Hi, I am the new member in your site. I have bought a C36R servo motor manufactured by cytron. I want to have the servo motor controlled by PIC16F873A microncontroller with 20MHz external crystal oscillator.

I have tried to connect the servo motor to my programmed mcu...but the result manifested is very weird, the servo was keep vibrating and turning in an inconsistent fashion. Besides, the servo acts differently everytime I switch on.

I know to activate the servo we need 20ms period or 50Hz frequency, I have measured the pwm signal generated from my mcu using oscilloscope, the value for the period is around 22ms or 44Hz, is it the reason why the servo can't work properly?

I have check my codes for several times, I think my calculation for the period is correct. Please help thanks a lot.

I set 1ms and 2ms pulse width in my codes for servo to turn counterclockwise and clockwise respectively.
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Re: C36R servo motor

Postby shahrul » Thu Feb 10, 2011 8:04 pm

Did you program single servo? You can see this example code and video. Servo Lesson.

If you connect more servo, it's maybe problem form the supply source if you use voltage regulator.
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Re: C36R servo motor

Postby robosang » Thu Feb 10, 2011 8:07 pm

mostly is power not enough 8-)
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Re: C36R servo motor

Postby picpicpikapika » Fri Feb 11, 2011 6:30 am

I am using one servo only, and my servo is supplied with 5V from 7805 voltage regulator, the inital voltage is 9V.
So, the shortage of current or power is not the problem right?
Is it ok to drive the servo with 22ms period or 44.4Hz frequency??? Thanks a lot.
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Re: C36R servo motor

Postby shahrul » Fri Feb 11, 2011 9:17 am

picpicpikapika WROTE:I am using one servo only, and my servo is supplied with 5V from 7805 voltage regulator, the inital voltage is 9V.
So, the shortage of current or power is not the problem right?
Is it ok to drive the servo with 22ms period or 44.4Hz frequency??? Thanks a lot.

Supply single servo with 5V from 7805 regulator, it's not problem.
I don't know servo works on 44.4Hz. It should 50Hz and increase up to 70Hz, it's still works.
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Re: C36R servo motor

Postby ober » Fri Feb 11, 2011 9:26 am

What is the source you are using? 9V battery? If you are using 9V battery, I would say that is the problem for unstable operation. if you are using adapter, what is the rated output current?
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Re: C36R servo motor

Postby picpicpikapika » Sat Feb 12, 2011 6:41 am

Yes I am using 9V battery as the input for my voltage regulator.
So, what is the frequency range for the servo to work properly(I know 50Hz is its initial frequency to drive it)?
What is the pulse width range for the servo to turn clockwise and counterclockwise. The C36R servo that I am using has pwm of min angle of 0.5ms and pwm of max angle of 2.35ms, is it ok if I supply 1ms for counterclockwise rotation and 2ms for clockwise rotation?
Thanks.
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Re: C36R servo motor

Postby ober » Sat Feb 12, 2011 8:40 am

9V battery is definatelly not sufficient to drive RC servo even is 1 pcs and under no load condition. Do change to other power source, preferable 1.5A continuous output current.

You can still try 44Hz, it should be working fine.
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Re: C36R servo motor

Postby picpicpikapika » Sat Feb 12, 2011 9:34 am

Thanks I will test it using DC power supply.
Therefore, apart from using adapter, can you suggest what is the other portable power supplies with 1.5A current?
According to the link in the first reply from Shahrul, a direct 6V battery to the servo will be able to drive it, is it true??
Thanks a lot.
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Re: C36R servo motor

Postby hyng » Sat Feb 12, 2011 10:34 am

you can use Lithium Polymer Battery or Lead Acid Battery. However, you still need to regulate the power to 5V or 6V. If you are using only one servo motor, then it is sufficient to use the normal regulator. If you need high current to drive many servos, you may refer to PR18 Schematic which is using power transistor to boost the current.
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