Using Servos With Arduino Made Easy !

Intro: Using Servos With Arduino Made Easy !

Servomotors or simply servos are essential components of a robot which convert electrical energy into mechanical energy.They are widely used in the field of RC hobby and robotics. But unlike simple geared motors , these servos are made by integrating a geared motor with a position feedback circuit which allows us to control the rotation of the shaft precisely. To drive a servo , we need a controller which provides PWM signals to the servo which in turn determines the angle of rotation. Using an arduino to do this is pretty easy job, all you need is :

1. A servo ( To make your own servo , check this out : make your own servo ! )

2. Arduino ( and the default "knob.ino" sketch )

3. A bunch of jumper wires ( male to male )

4. A 10k potentiometer

5. A USB cable

STEP 1: Prepare the Potentiometer

The potentiometer has three pins one is for the wiper and the other two have 10k resistance between them. The wiper should be connected to the analog 0 pin on the arduino , one of the remaining two pins should be connected to +5v and the other should be grounded. The potentiometer has been soldered on a protoboard to make it "arduino friendly" ( you can use a breadboard too ).

Based on how you rotate the the wiper arm , the analog values on the analog 0 pin will change and therefore the angle of rotation of the servo will also change.

STEP 2: Upload the Program and Attach the Servo

I've made some minor changes in the program :

pin 15 ( analog 1 ) and pin 16 ( analog 2 ) are used as power source for the potentiometer board.

The arduino reads values from potentiometer between 0 and 1023

" val = analogRead(potpin); "

Then it converts or "maps" the values from 0-1023 to 0-179 ( in degrees )

" val = map(val , 0 , 1023 , 0 , 179 ); "

Finally , it writes these values to the servo.

CONNECTIONS :

1. Connect the potentiometer to the arduino ( as mentioned above )

2. Attach the yellow/orange signal pin of servo to pin 9 on arduino.

3. Connect the red wire to VIN pin* and the brown one to ground.

4. Take power from USB.

5. Upload the attached sketch to arduino.

***IF you are using external power source ( other than USB ) then first convert the voltage to 5v.

>> some important tips

STEP 3: Troubleshooting and Tips

TIPS :

1. Do Not take +5v from any pin on arduino or from the +5v pin on arduino , I'm saying this because sometimes servos tend to draw high current from the source which can seriously damage the microcontroller. Instead use lithium batteries or any other batteries to power-up your servo ( USB power also works quite well ).

2. If your arduino keeps on resetting and the servo behaves abnormally , try adding capacitors to your power supply.

3. You can use optoisolators / optocouplers to electrically isolate the servo from microcontroller. This keeps the high current away from the microcontroller and stops the noises from damaging the controller.

At last , feel free to ask your questions

and if you find my instructable helpful , please do vote for me :)

Comments

[TheCoffeeDude]

Love Arduino tutorials. Great one!

[electro18]

Thanks ! :)

[dtare]

What if i need to control multiple servos..with multiple potentiometers...what would be the code?

[bocabearing]

Hello. I got an instructable where I show how to control 3 servos with 3 potentiometers. Maybe it can help you. https://m.instructables.com/id/Simple-Robotic-Arm-Out-of-Cardboard-Pieces/

[dtare]

thanks dude :)

[ibenkos]

I made it and made a door lock out of it :)

[nitishdash2010]

how? can you share?

[farsadheidari]

thank you very good

[DCengineer]

How much noise do you get? I've tried working with servos before, and they tend to get a lot of noise from the PWM. This is partially due to servo quality, however, I think a small capacitor on the signal line can help. Unfortunately, I have no working servos at this time, I'll have to try building one like you said.

[electro18]

While using these micro servos , I usually get a lot of noise followed by jittering. Adding a bunch of capacitors to the power pins turns out to be helpful but I've not tried adding them to the signal pin.

[DCengineer]

I'm not sure, it may be the power pin after all. However, it makes more since to me to put it on the signal pin. Just be sure not to put a big one there, that will make the signal constant (as opposed to pulses). Either way, I would suggest researching before putting a cap on the signal pin. It could cause problems.

[electro18]

I don't have an oscilloscope or any other device to monitor PWM pulses but I suspect that the power source is not capable of delivering steady current.

[billbillt]

Why is that??...

[electro18]

Hey there, billbillt !

Sorry for the late reply but I didn't get your question.

[DCengineer]

It could also be your supply power. If you are powering servos via USB, I would suggest not doing it. Even if you system does turn off the USB port if you draw too much (which I have had happen), running motors via your computer could damage it. The Arduino is a fairly resilient device that runs on 5v power. Computers run on various amounts (the CPU I believe typically runs on 3.3v, and RAM can run on 2 or even 1v. Moral of the story: it is a lot cheaper to replace the ATmega chip on an Arduino than it is to replace the port board, RAM, or CPU of a computer (if the safeguards don't exist or fail).

Exception: you should be fine running off of a phone or tablet charger. Simple ones (read: non-Apple) basically just output 5v at 500mA on the outer two pins. The inner pins are for data transfer.

[electro18]

Yeah , I was getting the same problem since then I'm using a 12V SLA battery to power up the servo.

[szaffarano1]

I used a Mophie to power my Adruino Uno, for 5 servos, and 2 LEDs, and it worked great!! There are pics and a video of the completed project on here, under the Animatronic Horus helmet build. I could have used some of your additional information sooner, but it will help make this costume more functional by halloween 2014!! Thanks!!

[electro18]

Good luck for your project ! :)

[szaffarano1]

Thanks! It's coming along well! I plan to use a smaller board to solder the wires to and make the electronics more permanent for the helmet. Should be more, 'wearable' for halloween!

[electro18]

Sounds awesome :) ! I can't wait to see it on instructables !