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62 lines
2.2 KiB
JavaScript
62 lines
2.2 KiB
JavaScript
/*
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* Author: Mihai Tudor Panu <mihai.tudor.panu@intel.com>
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* Copyright (c) 2016 Intel Corporation.
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*
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* This program and the accompanying materials are made available under the
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* terms of the The MIT License which is available at
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* https://opensource.org/licenses/MIT.
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*
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* SPDX-License-Identifier: MIT
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*/
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/* This example demonstrates how to use one of the ADS1115 ADCs on the
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* DFRobot Joule Shield with devices that output a small differential
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* voltage (e.g. geophones, piezoelectric bands or pads, thermocouples).
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*/
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var mraa = require('mraa'); // Not used directly but required if jsupm_ads1x15 was installed from NPM
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var upm = require('jsupm_ads1x15');
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var fs = require('fs'); // Values will be written to a file
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var file = "./ads1115.data" // Output filename
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var id = 0; // Sample number
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var ival; // Interval function for sampling
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// There are two ADS1115 chips on the DFRobot Joule Shield on the same I2C bus
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// - 0x48 gives access to pins A0 - A3
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// - 0x49 gives access to pins A4 - A7
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var ads1115 = new upm.ADS1115(0, 0x48);
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// Configure the ADS1115 for the SM-24 Geophone
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// Put the ADC into differential mode for pins A0 and A1,
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// the SM-24 Geophone is connected to these pins
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ads1115.getSample(upm.ADS1X15_MUX_DIFF_0_1);
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// Set the gain based on expected VIN range to -/+ 2.048 V
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// Can be adjusted based on application to as low as -/+ 0.256 V, see API
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// documentation for details
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ads1115.setGain(upm.ADS1X15.GAIN_TWO);
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// Set the sample rate to 860 samples per second (max) and turn on continuous
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// sampling
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ads1115.setSPS(upm.ADS1115.SPS_860);
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ads1115.setContinuous(true);
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// Open the output file and start reading data once open
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// Will overwrite file if it already exists
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var stream = fs.createWriteStream(file);
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stream.once('open', function() {
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ival = setInterval(function() {
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// Write data pairs of ID + Value for easy plotting
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stream.write(id + " " + ads1115.getLastSample().toFixed(7) + "\n");
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id++;
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}, 1); // Wait 1 ms between reads, (actuall call adds another ~1 ms overhead)
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});
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// Stop after 10 seconds and close the file
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setTimeout(function() {
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clearInterval(ival);
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stream.end();
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console.log("Wrote " + id + " samples to file: " + file);
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}, 10000);
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