hey i was trying to control the servo using joystick(potentiometer).
i am but stuck at a problem
when joystick is at center servo is at 90° when i move the joystick to left, servo sets at 0° and when i release the joystick it came back to its 90° but when i move the joystick to right, the server does sets to 180° but does not come back to 90° on release the joystick, it sets to a little more than 90° like 100°
what could be the problem ?

#include <Servo.h>
Servo servo;
int sp ;
int js_x;
void setup()
{
servo.attach(3);
}
void loop()
{
  sp= map(js_x ,0 ,1023, 0, 180);
   servo.write(sp);
}

Mod edit: code tags

 

Missing ADC code.

 

Might not be a code problem, could be joystick hysteresis.

Move the joystick and read the voltage with a voltmeter, see if it returns to the same value each way.

 

And a third thing.
Uno ADC is unipolar(?). Meaning it is from 0 to +5V, which digitally is 0 to 255 for 8 bit, 0 to 1023 for 10 bit.

You joystick might be bipolar. -X volts for left, 0V for center, +X volts for right. Digitally, for 8 bit ADC, it would be -128 for left, 0 for center, 127 for right.
So.
If your joystick is bipolar, then Uno ADC never sees the negative voltages because it can only go down to 0 volts, anything lower than 0 volts will simply be seen as 0 volts.

 

The arduino uno returns a 10bit value on analogRead().

I don't see how the original code works as there is no analogRead() to get the adc value. Actual code that shows the problem wold help.

 

Might not be a code problem, could be joystick hysteresis.

Move the joystick and read the voltage with a voltmeter, see if it returns to the same value each way.

+1. the pot shaft in your joystick may be slipping, or may just just be a crappy pot.

 

The arduino uno returns a 10bit value on analogRead().

I don't see how the original code works as there is no analogRead() to get the adc value. Actual code that shows the problem wold help.

You are right. My error.