mirror of https://github.com/espruino/BangleApps
72 lines
2.3 KiB
JavaScript
72 lines
2.3 KiB
JavaScript
Bangle.setBarometerPower(true, "altimeter");
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g.clear(1);
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Bangle.loadWidgets();
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Bangle.drawWidgets();
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var zero = 0;
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var R = Bangle.appRect;
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var y = R.y + R.h/2;
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var MEDIANLENGTH = 20;
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var avr = [], median;
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var value = 0;
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function getStandardPressure(altitude) {
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const P0 = 1013.25; // standard pressure at sea level in hPa
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const T0 = 288.15; // standard temperature at sea level in K
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const g0 = 9.80665; // standard gravitational acceleration in m/s^2
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const R = 8.31432; // gas constant in J/(mol*K)
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const M = 0.0289644; // molar mass of air in kg/mol
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const L = -0.0065; // temperature lapse rate in K/m
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const temperature = T0 + L * altitude; // temperature at the given altitude
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const pressure = P0 * Math.pow((temperature / T0), (-g0 * M) / (R * L)); // pressure at the given altitude
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return pressure;
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}
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function convertToSeaLevelPressure(pressure, altitude) {
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return 1013.25 * (pressure / getStandardPressure(altitude));
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}
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Bangle.on('pressure', function(e) {
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while (avr.length>MEDIANLENGTH) avr.pop();
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avr.unshift(e.altitude);
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median = avr.slice().sort();
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g.reset().clearRect(0,y-30,g.getWidth()-10,R.h);
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if (median.length>10) {
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var mid = median.length>>1;
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value = E.sum(median.slice(mid-4,mid+5)) / 9;
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t = value-zero;
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if ((t > -100) && (t < 1000))
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t = t.toFixed(1);
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else
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t = t.toFixed(0);
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g.setFont("Vector",50).setFontAlign(0,0).drawString(t, g.getWidth()/2, y);
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sea = convertToSeaLevelPressure(e.pressure, value-zero);
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t = sea.toFixed(1) + " " + e.temperature.toFixed(1);
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if (0) {
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print("alt raw:", value.toFixed(1));
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print("temperature:", e.temperature);
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print("pressure:", e.pressure);
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print("sea pressure:", sea);
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print("std pressure:", getStandardPressure(value-zero));
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}
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g.setFont("Vector",25).setFontAlign(-1,0).drawString(t,
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10, R.y+R.h - 35);
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}
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});
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print(g.getFonts());
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g.reset();
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g.setFont("Vector:15");
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g.setFontAlign(0,0);
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g.drawString(/*LANG*/"ALTITUDE (m)", g.getWidth()/2, y-40);
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g.drawString(/*LANG*/"SEA L (hPa) TEMP (C)", g.getWidth()/2, y+62);
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g.flip();
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g.setFont("6x8").setFontAlign(0,0,3).drawString(/*LANG*/"ZERO", g.getWidth()-5, g.getHeight()/2);
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Bangle.setUI("updown", btn=> {
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if (!btn) zero=value;
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if (btn<0) zero-=5;
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if (btn>0) zero+=5;
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});
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