36 lines
992 B
JavaScript
36 lines
992 B
JavaScript
"use strict";
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module.exports = {
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/**
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* Calculates PWM Period and Duty based on provided params.
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*
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* @param {Number} scaledDuty the scaled duty value
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* @param {Number} freq frequency to use
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* @param {Number} pulseWidth pulse width
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* @param {String} [polarity=high] polarity value (high or low)
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* @return {Object} calculated period and duty encapsulated in an object
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*/
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periodAndDuty: function(scaledDuty, freq, pulseWidth, polarity) {
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var period, duty, maxDuty;
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polarity = polarity || "high";
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period = Math.round(1.0e9 / freq);
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if (pulseWidth != null) {
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var pulseWidthMin = pulseWidth.min * 1000,
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pulseWidthMax = pulseWidth.max * 1000;
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maxDuty = pulseWidthMax - pulseWidthMin;
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duty = Math.round(pulseWidthMin + (maxDuty * scaledDuty));
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} else {
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duty = Math.round(period * scaledDuty);
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}
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if (polarity === "low") {
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duty = period - duty;
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}
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return { period: period, duty: duty };
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}
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};
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