Servo Jitter

@Chris Gomersall

I'm also working on this problem, I do not think the problem comes from speed.

Try this sketch!

The servo will position itself in weak abutment, wait and watch the arm of the servo, it is necessary to be attentive.

Press "Send" when the servo starts to move. The start value is captured.

Then the servo arm will move to a high stop, wait and watch the servo arm.

Press "Send" again when the servo starts to move. The end value is captured.

It may be necessary to change the start and end search values (StartLower and StartUpper) to be sure to be in range.

Repeat the test to be sure.

/*************************************

Simple Arduino sketch to find the full pulse width range of a servo.

It does so by starting with a low pulse width and to increase it in small steps. Once

you see movement the minimal pulse width is reached. Press "Send" in the serial monitor to

indicate that to the program.

Note: The code is written in a simple blocking way and not optimized. It's a terrible

startingpoint to use in your own code!

INSTRUCTIONS

- Set Serial Monitor to 115200 baud

- Set Serial Monitor to "Both NL & CR"

- Connect a servo to 'ServoPin' (default: pin 10)

- Press "Send" when the Servo starts moving (for both lower and upper limit)

- When the limits are reached, the servo will alternate between them

- Press reset to start over

*************************************/

#include <Servo.h>

const byte ServoPin = 10;

//Minimal pulse width to try for lower limit (in ms)

const unsigned int StartLower = 500;

//maximal pulse width to try for upper limit (in ms)

const unsigned int StartUpper = 2500;

//Number to increment the pulse width during search (in ms)

const unsigned int StepSize = 11;

//time between increments (in ms)

const unsigned int StepInterval = 1000;

unsigned int lowerLimit;

unsigned int upperLimit;

Servo testServo;

void setup(){

Serial.begin(115200);

Serial.println("Servo pulse width finder sketch");

Serial.println();

Serial.println("Be sure to set Serial monitor to \"Both NL & CR\".");

Serial.println("Press \"Send\" when the servo starts moving during the search.");

Serial.println();

//move servo already to lower end and attach it

testServo.write(0);

testServo.attach(ServoPin, StartLower, StartUpper);

Serial.print("Searching for lower limit");

lowerLimit = sweep(StartLower, StepSize, StepInterval);

printResult("Lower", lowerLimit);

Serial.print("Searching for upper limit");

//minus the 'StepSize' to go the other way

upperLimit = sweep(StartUpper, -StepSize, StepInterval);

printResult("Upper", upperLimit);

Serial.println("Press reset to test again.");

}

void loop(){

testServo.writeMicroseconds(lowerLimit);

delay(2000);

testServo.writeMicroseconds(upperLimit);

delay(2000);

}

unsigned int sweep(unsigned int start, int delta, unsigned int interval){

testServo.writeMicroseconds(start);

delay(interval);

unsigned int value = start;

//stop the search if we receive something on Serial

while(!Serial.available()){

//increase the value to the new position

value += delta;

//stop searching if we go beyond the start positions of the search (= Failed)

if((value < StartLower) || (value > StartUpper)){

Serial.println();

return 0;

}

//otherwise move to new position

testServo.writeMicroseconds(value);

Serial.print(".");

delay(interval);

}

clearSerialBuffer();

Serial.println();

//

return value;

}

void printResult(char *text, unsigned int value){

//value found

if(value != 0){

Serial.print(text);

Serial.print(" limit: ");

Serial.print(value);

Serial.println("ms");

}

//value not found

else{

Serial.print(text);

Serial.println(" limit not found!");

Serial.println("Press reset to try again.");

//and stop here

while(true);

}

}

void clearSerialBuffer(){

//clear serial buffer (but do nothing with it)

while(Serial.available()){

Serial.read();

}

}

@Chris Gomersall

I advise you to search outside Nybble. Make a small assembly (print + arm + servo) to have the real range.