Servo Pi Library

AB Electronics UK Servo Pi Node.js Library

Node.js Library to use with Servo Pi Raspberry PWM servo control board from https://www.abelectronics.co.uk

Install

To download to your Raspberry Pi type in terminal:

git clone https://github.com/abelectronicsuk/ABElectronics_NodeJS_Libraries.git

The Servo Pi library is located in the /lib/servopi/ directory

The example files are located in the /examples/servopi/ directory

The Servo Pi library requires the rpio library to run.

Install from https://www.npmjs.com/package/rpio with

npm install rpio

Functions:

setPWMFrequency(freq) 

Set the PWM frequency Parameters: freq - required frequency
Returns: null

setPWM(channel, on, off) 

Set the output on single channels Parameters: channel - 1 to 16, on - time period, off - time period Returns: null

setAllPWM( on, off) 

Set the output on all channels Parameters: on - time period, off - time period Returns: null

outputDisable()

Disable the output via OE pin Parameters: null Returns: null

outputEnable()

Enable the output via OE pin Parameters: null Returns: null

setAllCallAddress(address)

Set the I2C address for the All Call function Parameters: address Returns: null

enableAllCallAddress()

Enable the I2C address for the All Call function Parameters: null Returns: null

disableAllCallAddress()

Disable the I2C address for the All Call function Parameters: null Returns: null

Usage

To use the Servo Pi library in your code you must first import the library:

var servopi = require('../../lib/servopi/servopi')

Next you must initialise the ServoPi object:

var pwm = new ServoPi(0x40);

Set PWM frequency to 60 Hz

pwm.setPWMFrequency(60);
pwm.outputEnable();

Create a positions array and a counter variable

var positions = [250, 375, 500];
var count = 0;

Create a timer object and move the servo on port 0 between three points

var myTimer = setInterval(clockTimer, 1000);

function clockTimer() {
    // move the
    pwm.setPWM(0, 0, positions[count]);
    count++;
    if (count > positions.length) {
        count = 0;
    }
}