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pi-blaster.js
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pi-blaster.js
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var fs = require('fs');
/**
* Default pi-blaster file path
* @type {string}
*/
var PI_BLASTER_PATH = '/dev/pi-blaster';
/**
* We need to use write() with a buffer so that we can pass the position=-1 argument.
* This is needed, otherwise we get an error because node default write tries to seek
* in the file which is not possible (it's a FIFO).
* @param {String} cmd Command to be written
* @param {Function} callback Must accept only one optional error parameter
*/
function writeCommand(cmd, callback) {
var buffer = new Buffer(cmd + '\n');
var fd = fs.open(PI_BLASTER_PATH, 'w', undefined, function(err, fd) {
if (err) {
if (callback && typeof callback == 'function') {callback(err)};
} else {
fs.write(fd, buffer, 0, buffer.length, -1, function(error, written, buffer) {
if (error) {
if (callback && typeof callback == 'function') {callback(error)};
} else {
fs.close(fd, function (err) {
if (err) callback (err);
});
if (callback && typeof callback == 'function') {callback()};
}
});
}
});
}
/**
* Set a given pin to a given value
* @memberof module:pi-blaster
* @param {Integer} pinNumber Target pin {@link https://github.com/sarfata/pi-blaster/blob/master/pi-blaster.c#L39-51|Known pins}
* @param {Float} value Must be between 0 and 1
* @param {Function} callback Must accept only one optional error parameter
*/
function setPwm(pinNumber, value, callback) {
writeCommand(pinNumber + '=' + value, callback);
}
/**
* Release a pin (after release, this pin can be used by others as a regular GPIO pin)
* @memberof module:pi-blaster
* @param {Integer} pinNumber Target pin {@link https://github.com/sarfata/pi-blaster/blob/master/pi-blaster.c#L39-51|Known pins}
* @param {Function} callback Must accept only one optional error parameter
*/
function release(pinNumber, callback) {
writeCommand('release ' + pinNumber, callback);
}
/**
* NodeJS library for the {@link https://github.com/sarfata/pi-blaster|pi-blaster daemon.}
* @module pi-blaster
*/
module.exports = {
setPwm: setPwm,
release: release
}