Continuous servo wont completely stop

Using Arduino Programming Questions
1

hello i have found a solar tracker project from the internet it simply uses two LDR's and a hacked continuous servo to spin it. i have got it all working fine but when i try to tell the servo to stop in sketch using (myservo.write 90) it doesn't completely stop the servo. i have since found that myservo.write 92 is a little closer to stopping it but it still turns slightly every 4 or 5 seconds. in another sketch i have used myservo.writemicroseconds 1500 and that stops the servo alot better. what i am wondering is, in my code i cant figure out how to substitute myservo.write pos to myservo.writemicroseconds every time i do it just spins backwards and forwards without stopping.
any help would be greatly appreciated.
thank you

#include <Servo.h>

int ServoOut = 9;
int photoPinLeft = 0;
int photoPinRight = 5;
int LeftReading;
int RightReading;
int pos;
int tolerance = 20; /* +/- the total difference 
between the two photoresistors. You can test 
this by covering both the resistors in total darkness, 
and note the difference between the two readings. */

Servo myservo;

void setup()
{
myservo.attach(ServoOut);
Serial.begin(9600);
}

void loop()
{
LeftReading = analogRead(photoPinLeft);
RightReading = analogRead(photoPinRight);

Serial.print("Left Reading = ");
Serial.println(LeftReading);
Serial.print("Right Reading = ");
Serial.println(RightReading);

if(LeftReading > RightReading + tolerance)
{
pos = 94;
}
else if(LeftReading + tolerance < RightReading)
{
pos = 88;
}
else
{
pos = 92;
}

myservo.write(pos);
delay(120);
}
2

i cant figure out how to substitute myservo.write pos to myservo.writemicroseconds

I don't understand, - you say you've used writeMicroseconds in another sketch, but you can't use it here?
Did you remember to change the range of the variables from "angles" to microseconds?

3

yea you are spot on. i have figured it out now. for some reason i left the servo.write(pos) at the bottom when substituting the servo.writemicroseconds.
thanks for help

4

I haven't tried the below specific code with a servo, but if you have problems with the continuous rotation servo starting to creep at its stopped command value, you might instead try detaching the servo.

// zoomkat 10-14-11 serial servo test
// type servo position 500 to 2500 in serial monitor
// type in number 1500 to detach servo
// for IDE 0022 and later
// Powering a servo from the arduino usually DOES NOT WORK.

String readString;
#include <Servo.h> 
Servo myservo;  // create servo object to control a servo 

void setup() {
  Serial.begin(9600);
  myservo.writeMicroseconds(1500); //set initial servo position if desired
  myservo.attach(7);  //the pin for the servo control 
  Serial.println("servo-test-22"); // so I can keep track of what is loaded
}

void loop() {
  while (Serial.available()) {
    char c = Serial.read();  //gets one byte from serial buffer
    readString += c; //makes the string readString
    delay(2);  // allow buffer to fill with next character
    }

  if (readString.length() >0) {
    Serial.println(readString);  //so you can see the captured string 
    int n = readString.toInt();
    
    if (n == 1500) {
      myservo.detach(); 
    }
    else {
       myservo.attach(7);
       myservo.writeMicroseconds(n); //convert readString to number for servo
    }
    readString=""; //empty for next input
  } 
}
5