pca9685

PCA9685 I2C 16-channel PWM/servo driver module


This is an npm module that can interact with the PCA9685 I2C 16-channel
PWM/servo driver. Information on the PCA9685 can be found
here
and it is available for purchase at
Adafruit.

Usage

``js
var i2cBus = require("i2c-bus");
var Pca9685Driver = require("pca9685").Pca9685Driver;

var options = {
i2c: i2cBus.openSync(1),
address: 0x40,
frequency: 50,
debug: false
};
pwm = new Pca9685Driver(options, function(err) {
if (err) {
console.error("Error initializing PCA9685");
process.exit(-1);
}
console.log("Initialization done");

// Set channel 0 to turn on on step 42 and off on step 255
// (with optional callback)
pwm.setPulseRange(0, 42, 255, function() {
if (err) {
console.error("Error setting pulse range.");
} else {
console.log("Pulse range set.");
}
});

// Set the pulse length to 1500 microseconds for channel 2
pwm.setPulseLength(2, 1500);

// Set the duty cycle to 25% for channel 8
pwm.setDutyCycle(8, 0.25);

// Turn off all power to channel 6
// (with optional callback)
pwm.channelOff(6, function() {
if (err) {
console.error("Error turning off channel.");
} else {
console.log("Channel 6 is off.");
}
});

// Turn on channel 3 (100% power)
pwm.channelOn(3);
});
`

Note that you need to construct the i2c-bus
object and pass it in to the module along with the I2C address of the PCA9685
PWM/servo driver.

Options

- i2c: The I2cBus object used to communicate to the PWM/servo driver.
- address: The I2C address of the PCA9685 PWM/servo driver.
- frequency: The frequency to use for the PWM/servo driver. 50 is
standard for servos, but higher frequencies might work better for
driving LEDs without obvious flicker.
- debug: If truthy, then debug messages will be printed on the console
during operations.

Debugging

This project uses the debug library for
debugging. This allows you to enable debugging using environment variables or in
code before constructing the Pca9685Driver object. The name of the debugging
stream produced by the library is pca9685.See the debug library documentation
for more information.

TypeScript

This project is written in TypeScript. The
library can be used by plain JavaScript as shown above, and the typing
information is also included with the library so that anyone wishing to use
Typescript will gain the benefits of the type information.

Acknowledgements

This module was based on
Adafruit's Raspberry-Pi Python Code Library
and
the adafruit-i2c-pwm-driver` NPM module.