Goal:
To move servos with the Arduino to a
position, and stay there (without the servo
library).
Arduino Controlling the Servo!
Housekeeping Blurb
This tutorial is about moving servos with
the Arduino. It is aimed at people that have used the Arduino to
make LEDs blink, or something simple. You will NOT learn about PWM
in this tutorial. However, at the end of the tutorial, I hope that
you will have the ability to move servos in any fashion you wish
with the Arduino! Before we begin, I must say that I adapted my
code from Tod E. Kurt's code, which was adapted from Daniel's code,
which was adapted from Tom Igoe and Jeff Gray's "Temporary Servo
Function" code. I'll be using Draganfly DF-06 servos - but you can
adapt the code to any servo that you'd wish! Now that the
housekeeping is out of the way, let's start!
Draganfly DF-06 Servo
Part 1 -
Light Salad
This
part will be the prelude to the meat and potatoes part. It is good
if you would like a solid background!
First,
let's plug in our servos. I always had trouble with this, so here
is a straight forward breakdown.
Black -> Ground (0V)
Red -> Power (5V)
White/Yellow -> Control (PWM) * See the
next few lines directly below for more info on where to plug it
in!
At the top of the Arduino there are several Digital Output pins. Let's plug the data cable (control) of Servo #1 into pin #7, and Servo #2 into pin #6. Let's define this in the code that will be loaded onto the Arduino:
At the top of the Arduino there are several Digital Output pins. Let's plug the data cable (control) of Servo #1 into pin #7, and Servo #2 into pin #6. Let's define this in the code that will be loaded onto the Arduino:
int servo1 = 7;
int servo2 = 6;
While you're at it, we also have to define a few other things, myAngle and pulseWidth. There is one for each servo. The explanation of each will follow.
int myAngle1;
int myAngle2;
int pulseWidth1;
int pulseWidth2;
myAngle is used for defining where you want
the servo to be. If you set it to 0, it will be all the way to the
right. If you set it to 180, it will be all the way to the left! 90
will be in the middle.
pulseWidth converts the angle to microseconds. You will definitely have to play around with this if you will be using different servos. I used trial and error to get the values to work for the Draganfly servos. I did try this with a Kondo servo, and it worked well! It all depends. Sometimes you may have to tinker with it, sometimes not.
Now, we have to have two methods that we can call in the loop. So, we will call them servoPulse1 and servoPulse2.
Here is the code for each:
pulseWidth converts the angle to microseconds. You will definitely have to play around with this if you will be using different servos. I used trial and error to get the values to work for the Draganfly servos. I did try this with a Kondo servo, and it worked well! It all depends. Sometimes you may have to tinker with it, sometimes not.
Now, we have to have two methods that we can call in the loop. So, we will call them servoPulse1 and servoPulse2.
Here is the code for each:
*Note: This does not go into the void loop just yet!
void servoPulse1 (int servo1, int myAngle1) {
pulseWidth1 = (myAngle1 * 11) + 500; // Converts angle to microseconds
digitalWrite(servo1, HIGH); // Set servo high (turns it on)
delayMicroseconds(pulseWidth1); // Wait a very very small amount
digitalWrite(servo1, LOW); // Set servo low (turns it off)
delay(20); // Typical Refresh cycle of servo (20 ms)
}
void servoPulse2 (int servo2, int myAngle2) {
pulseWidth2 = (myAngle2 * 11) + 500; // Converts angle to microseconds
digitalWrite(servo2, HIGH); // Set servo high (turns it on)
delayMicroseconds(pulseWidth2); // Wait a very very small amount
digitalWrite(servo2, LOW); // Set servo low (turns it off)
delay(20); // Typical Refresh cycle of servo (20 ms)
}
What happens in this code? We change an angle into a pulse width, turn on the servo for the calculated time pulseWidth, then we turn the servo off!
Part 2 -
Meat & Mashed Potatoes
This part is the really good
stuff! It all connects in this part.Next is the void setup(). We just have to put our servo outputs here.
void setup() {
pinMode(servo1, OUTPUT);
pinMode(servo2, OUTPUT);
}
This means that servo1 (defined above as 7)
and servo2 (defined above as 6) will be outputs.
Now for the fun part - the loop! This is the main course of the meal, when it comes to the Arduino program. Here is the code, the explanation will follow!
Now for the fun part - the loop! This is the main course of the meal, when it comes to the Arduino program. Here is the code, the explanation will follow!
void loop() {
for (myAngle1=0; myAngle1<=180; myAngle1++) {
myAngle1 = 100;
myAngle2 = 90;
servoPulse1(servo1, myAngle1);
servoPulse2(servo2, myAngle2);
}
}
We make a
for loop so that the servo will not get caught in the Arduino loop.
Slightly confusing, but it works! The way I like to look at for
loops, is by looking at them by a while perspective. So, we start
off by saying that myAngle1 is 0. Now, we say while myAngle1 is
less than or equal to 180, we will increment myAngle (that's what
the myAngle1++ means). Okay, now we will set the first servo to 100
degrees. The second one will be set at 90 degrees. We now make sure
that the Arduino does move the servo to that angle by calling the
servoPulse method we created before.
Pretty neat stuff! It is now very simple for you to move your servo with Arduino. Basically, you just change myAngle1, call the servoPulse method, and your servo will move! I hope that this will help you more!
Pretty neat stuff! It is now very simple for you to move your servo with Arduino. Basically, you just change myAngle1, call the servoPulse method, and your servo will move! I hope that this will help you more!
Personally, my future goals with Arduino and
servos is to one day create an interface with Processing to make
knobby switches that will move the servos. From there, I may order
2 Arduinos, or somehow expand 1 Arduino, to have 18 servos so that
I am able to control my MANOI AT01 humanoid robot.
Please feel free to contact me if you have any further questions!
erin ~at~ robotgrrl.com OR you can message me on learnhub :)
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