JavaScript Robotics: ESC API (Johnny-Five)

Parameters
Shape
Component Initialization
Usage
API
Events

The ESC class constructs objects that represent a single ESC (Electronic Speed Control) component attached to the physical board. ESC objects are similar to Servo objects as they both use PWM pins to communicate with the physical ESC. Currently, this class assumes the ESC is pre-calibrated.

Parameters

pin A Number or String address for the ESC pin (PWM).
```
var esc = new five.ESC(9);
```

Options An object of property parameters.

Property	Type	Value/ Description	Default	Required
pin	Number, String	Any PWM Pin. The address of the PWM pin the ESC is attached to		yes
controller	String	DEFAULT, PCA9685. Controller interface type.	"DEFAULT"	no
pwmRange	Array	`[ min, max ]` The pulse width range in microseconds.	`[1000, 2000]`	no
device	String	FORWARD, FORWARD_REVERSE, FORWARD_BRAKE_REVERSE. Device capability type.	"FORWARD"	no
neutral	Number	Neutral point, usually the middle of the PWM range.	Varies by `device`	no

PCA9685 Options (controller: "PCA9685")

Property Type Value/Description Default Required

address Number I2C device address. 0x40 no

Property	Type	Value/Description	Default	Required
address	Number	I2C device address.	`0x40`	no

Shape

Property Name	Description	Read Only
`id`	A user definable id value. Defaults to a generated uid	No
`pin`	The pin address that the ESC is attached to	No
`neutral`	The stopped/brake-state value of the ESC, usually the middle of PWM range.	No
`pwmRange`	`[ min, max ]` The pulse width range in microseconds.	No

Component Initialization

Basic

new five.ESC(9);

ESC

ESC PCA9685

new five.ESC({
  device: "FORWARD_REVERSE",
  controller: "PCA9685",
  pin: 1
});

ESC

Bidirectional

new five.ESC({
  device: "FORWARD_REVERSE",   
  pin: 9, 
});

ESC

Usage

Standard, FORWARD-only ESC:

const five = require("johnny-five");
const board = new five.Board();

board.on("ready", function() {

  const esc = new five.ESC(11);
  const speed = 0;

  board.loop(100, () => {
    // limit to 10% for safety!
    if (speed < 10) {
      speed += 1;
      esc.throttle(speed);
    }
  });
});

API

speed(value) Deprecated. Use throttle(μs) or throttle(%)

throttle(μs|percentage) Throttle the speed of the ESC by setting a pulse in μs or percentage (0-100).

var esc = new five.ESC(9);

esc.throttle(1500); // 1500μs is half speed of a single direction or neutral of a bidirectional

esc.throttle(50); // 50% is half speed in a single direction or neutral of a bidirectional

brake() Brake the ESC

var esc = new five.ESC(9);

esc.brake();

Calibrating an ESC

This isn't a requirement, but if you experience issues with your ESCs, it might prove helpful

Load the following sketch onto your Arduino, via the Arduino IDE follow the instructions.

This requires that the ESC's power source is off or disconnected at the start of the calibration process. You will be prompted to turn on/reconnect the power during the process.

#include <Servo.h>

#define MAX_SIGNAL 2000
#define MIN_SIGNAL 1000
#define MOTOR_PIN 12

Servo motor;

void setup() {
  Serial.begin(9600);
  Serial.println("Program begin...");
  Serial.println("This program will calibrate the ESC.");

  motor.attach(MOTOR_PIN);

  Serial.println("Calibrating Maximum Signal");
  Serial.println("Turn on power source, then wait 2 seconds and press any key + <enter>");
  motor.writeMicroseconds(MAX_SIGNAL);

  // Wait for input
  while (!Serial.available());
  Serial.read();

  // Send min output
  Serial.println("Calibrating Minimum Signal");
  motor.writeMicroseconds(MIN_SIGNAL);

}

void loop() {  

}