forked from
fogtype.com/_
プレイグラウンド、サンドボックス、使い捨てスクリプト置き場
heat-rate (ads1x15 and analog heart rate sensor)
Kohei Watanabe
(Sep 27, 2025, 3:24 PM +0900)
0e7d97ed
1334030f
+125
+125
heart-rate/main.js
+125
heart-rate/main.js
···
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import ADS1X15 from "@chirimen/ads1x15";
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import { requestI2CAccess } from "node-web-i2c";
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async function readDataFromSensor(duration = 10000) {
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const i2cAccess = await requestI2CAccess();
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const ads1x15 = new ADS1X15(i2cAccess.ports.get(1), 0x48);
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await ads1x15.init(true);
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const values = [];
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const start = Date.now();
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while (Date.now() - start <= duration) {
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const output = await ads1x15.read(0);
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values.push(output);
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await new Promise((resolve) => setTimeout(resolve, 100));
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}
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return values;
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}
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/**
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* 移動平均除去AC成分を計算
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* @param values 入力値配列
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* @param windowSize 窓サイズ
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* @returns AC成分の配列
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*/
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function calculateAcValues(values, windowSize) {
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const acValues = [];
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for (let i = 0; i < values.length; i++) {
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const start = Math.max(0, i - Math.floor(windowSize / 2));
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const end = Math.min(values.length, i + Math.floor(windowSize / 2) + 1);
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const sum = values.slice(start, end).reduce((acc, val) => acc + val, 0);
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const average = sum / (end - start);
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acValues.push(values[i] - average);
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}
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return acValues;
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}
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/**
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* ピーク検出
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* @param values AC成分配列
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* @param minDistance 最小ピーク間隔
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* @returns ピークのインデックス配列
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*/
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function detectPeaks(values, minDistance) {
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const peaks = [];
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for (let i = 1; i < values.length - 1; i++) {
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if (
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values[i] > values[i - 1] &&
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values[i] > values[i + 1] &&
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values[i] > 0
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) {
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if (peaks.length === 0 || i - peaks[peaks.length - 1] >= minDistance) {
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peaks.push(i);
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}
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}
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}
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return peaks;
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}
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/**
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* 脈拍検出
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*/
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function detectHeartRate(values, samplingRate) {
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const minBPM = (2 * samplingRate * 60) / values.length;
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const maxBPM = 120;
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const windowSize = Math.round(samplingRate * 1); // 1秒の窓サイズ
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const minDistance = Math.round(samplingRate * 0.5); // 0.5秒の最小間隔
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const acValues = calculateAcValues(values, windowSize);
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const peaks = detectPeaks(acValues, minDistance);
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if (peaks.length < 2) {
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return null;
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}
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const intervals = [];
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for (let i = 1; i < peaks.length; i++) {
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intervals.push(peaks[i] - peaks[i - 1]);
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}
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const averageInterval =
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intervals.reduce((acc, val) => acc + val, 0) / intervals.length;
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const heartRate = Math.round((samplingRate * 60) / averageInterval);
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if (minBPM <= heartRate && heartRate <= maxBPM) {
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return heartRate;
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} else {
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console.log(
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`Heart rate ${heartRate} BPM is outside valid range (${minBPM.toFixed(
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1,
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)}-${maxBPM})`,
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);
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return null;
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}
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}
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console.log("Starting heart rate monitoring...");
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while (true) {
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console.log(`\n--- ${new Date().toLocaleTimeString()} ---`);
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try {
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const values = await readDataFromSensor(10000);
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const samplingRate = values.length / 10;
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console.log(`Data points: ${values.length}`);
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console.log(`Sampling rate: ${samplingRate} Hz`);
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console.log(`Data range: ${Math.min(...values)} - ${Math.max(...values)}`);
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const heartRate = detectHeartRate(values, samplingRate);
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console.log(
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`Detected Heart Rate: ${
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heartRate !== null ? heartRate + " BPM" : "Not detected"
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}`,
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);
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} catch (error) {
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console.error("Error reading sensor data:", error);
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console.log("Falling back to file data...");
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}
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}