servo-pca9685/examples/calibrate.js

Library to run the PCA9685 PWM driver.

// Any copyright is dedicated to the Public Domain.
// http://creativecommons.org/publicdomain/zero/1.0/

/*********************************************
This servo module demo allows you to find the
upper and lower PWM bounds your servo uses to
represent its maximum and minimum position.
These values should then be fed into that 
physical motor's `configure` function in order
to enable the motor to be commanded through 
its full range.

Run `tessel run calibrate.js` and try values 
until you find the upper and lower limits.

WARNING: If you use this code carelessly, you
run the risk of breaking your servo. Work 
your way out from the starting point slowly. 
*********************************************/

var tessel = require('tessel');
var servolib = require('../'); // Or 'servo-pca9685' in your own code

var servo = servolib.use(tessel.port['A']);

var servoNumber = 1; // Plug your servo or motor controller into port 1

// Reenable the console
process.stdin.resume();
console.log('Type in numbers between 0.0 and 1.0 to command the servo.');
console.log('Values between 0.05 and 0.15 are probably safe for most devices,');
console.log('but be careful and work your way out slowly.');
servo.on('ready', function () {
  // Start at a duty cycle of 10%
  var duty = 0.1;
  // Set the min and max duty cycle to 0% and 100%, 
  // respectively to give you the maximum flexibility  
  // and to eliminate math
  servo.configure(servoNumber, 0, 1, function () {
    // Move into the starting position
    servo.move(servoNumber, duty);
    // Enter command positions into the command line. Work 
    // your way outwards until the servo begins to stall 
    // (or the motor velocity remains constant). Note the
    // max an min values and use them in this *physical* 
    // motor/controller channel's `configure` call.
    // Once you configure the motor, arguments to `move` of
    // 0 and 1 will correspond to the minimum and maximum
    // PWM values given in the `configure` call, thereby
    // allowing you to easily command the actuator through
    // its full range of motion.
    process.stdin.on('data', function (duty) {
      duty = parseFloat(String(duty));
      console.log('Setting command position:', duty);
      servo.move(servoNumber, duty);
    });
  });
});