Datasheet

Using Feedback

If a servo motor does what it is to ld to do, why do we need feedback?

RC servos usually do what they are told to do, but there are many cases where a servo motor

might not. These can include:

Insufficient motor size

Insufficient power supply

Physical interference

Electrical interference

loose connection

In these cases, feedback could alert you to the problem.

But even if the servo is adequately sized and functioning normally, it still takes some time to

respond to a position command, and in many applications it is just as important to know when

the position is reached.

This following code snippet is from the "Sweep" example in the Servo library. Note the arbitrary

15 millisecond delay after

"myservo.write(val)".

Without feedback, most servo programming has to make some assumptions about how long a

particular move will take. Adding fixed-time delays to servo code works OK for simple

applications, but can result in slow and/or jerky performance when trying to coordinate multiple

servo motions or interactions between servos and other sensors or actuators.

Or worse: If the delays are not long enough, your servos may not reach the desired position in

time. This can cause malfunctions and/or damage to your project. Timing problems are a big

problem in battery-powered projects because the motors will run slower as the battery power

fades.

void loop()

{

val = analogRead(potpin); // reads the value of the potentiometer (value between 0 and 1023)

val = map(val, 0, 1023, 0, 179); // scale it to use it with the servo (value between 0 and 180)

myservo.write(val); // sets the servo position according to the scaled value

delay(15); // waits for the servo to get there

}