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index.js
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index.js
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var i2c = require('i2c');
var async = require('async');
var address = 0x53;
/**
*
* @param {Object} vars
* @param {Object} callback
*/
function ADXL345(callback)
{
this.SAMPLECOUNT = 400;
this.accelScaleFactor = [0.0,0.0,0.0];
this.runTimeAccelBias = [0, 0, 0];
this.accelOneG = 0.0;
this.meterPerSecSec = [0.0,0.0,0.0];
this.accelSample = [0,0,0];
this.accelSampleCount = 0;
//init stuff here
this.wire = new i2c(address, {
device : '/dev/i2c-1'
});
var self = this;
async.waterfall([
function(cb) {
self.wire.writeBytes(0x2D, [1 << 3], function(err) {
cb(err);
});
},
function(cb) {
self.wire.writeBytes(0x31, [0x09], function(err) {
cb(err);
});
},
function(cb) {
self.wire.writeBytes(0x2C, [8 + 2 + 1], function(err) {
cb(err);
});
}], function(err) {
if (!err) {
setTimeout(function() {
callback(null);
}, 10);
} else {
callback(err);
}
});
}
ADXL345.prototype.measureAccel = function(callback) {
var self = this;
this.wire.readBytes(0x32, 6, function(err, res) {
if (!err) {
for (var axis = XAXIS; axis <= ZAXIS; axis++) {
self.meterPerSecSec[axis] = res.readInt16LE(axis*2) * self.accelScaleFactor[axis] + self.runTimeAccelBias[axis];
}
callback(null);
} else {
callback(err);
}
});
}
ADXL345.prototype.measureAccelSum = function(callback) {
//get values from sensor here
var self = this;
this.wire.readBytes(0x32, 6, function(err, res) {
if (!err) {
for (var axis = XAXIS; axis <= ZAXIS; axis++) {
self.accelSample[axis] += res.readInt16LE(axis*2)
}
self.accelSampleCount++;
callback(null);
} else {
callback(err);
}
});
}
ADXL345.prototype.evaluateMetersPerSec = function() {
for (var axis = XAXIS; axis <= ZAXIS; axis++) {
this.meterPerSecSec[axis] = (this.accelSample[axis] / this.accelSampleCount) * this.accelScaleFactor[axis] + this.runTimeAccelBias[axis];
this.accelSample[axis] = 0;
}
this.accelSampleCount = 0;
}
ADXL345.prototype.computeAccelBias = function(callback) {
var self = this;
function getSamples() {
if (self.accelSampleCount < self.SAMPLECOUNT) {
self.measureAccelSum(function() {
setTimeout(getSamples, 2.5);
});
} else {
for (var axis = 0; axis < 3; axis++) {
self.meterPerSecSec[axis] = (self.accelSample[axis] / self.SAMPLECOUNT) * self.accelScaleFactor[axis];
self.accelSample[axis] = 0;
}
self.accelSampleCount = 0;
self.runTimeAccelBias[XAXIS] = -self.meterPerSecSec[XAXIS];
self.runTimeAccelBias[YAXIS] = -self.meterPerSecSec[YAXIS];
self.runTimeAccelBias[ZAXIS] = -9.8065 - self.meterPerSecSec[ZAXIS];
self.accelOneG = Math.abs(self.meterPerSecSec[ZAXIS] + self.runTimeAccelBias[ZAXIS]);
callback();
}
}
getSamples();
}
module.exports = ADXL345;