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--- iothings:laboratoare:2025:lab1 [2025/09/25 19:41]
dan.tudose [First Steps]
+++ iothings:laboratoare:2025:lab1 [2025/09/25 22:37] (current)
dan.tudose
@@ Line 24: / Line 24: @@
 After downloading and installing the PlatformIO extension, create a new project using any ESP32-C6 board. After project creation, you will need to edit the platformio.ini file and replace it with the following:
 <code bash platformio.ini>
 ; PlatformIO Project Configuration File
@@ Line 39: / Line 40: @@
 board = esp32-c6-devkitm-1
 framework = arduino
+; use SPIFFS for on-board files
+board_build.filesystem = spiffs
 build_flags =
@@ Line 51: / Line 54: @@
   adafruit/Adafruit GFX Library@^1.11.9
   adafruit/Adafruit SSD1306@^2.5.10
+  adafruit/Adafruit BME680 Library
   dantudose/LTR308 library@^1.0
   https://github.com/sparkfun/SparkFun_MAX1704x_Fuel_Gauge_Arduino_Library
   h2zero/NimBLE-Arduino@^2.1.0
 </code>
@@ Line 107: / Line 112: @@
 </code>
+=== 3. Bringing up the sensors ===
-=== 3. Scan and display local WiFi networks ===
+Now, let's do a quick sensor bring-up for the BME680 (temperature, humidity, pressure and gas). The sensor is connected on the I2C bus. Use the code below to read values over the serial terminal.
-Load this WiFi scanner code:
+<code C main.cpp>
+#include <Arduino.h>
+#include <Wire.h>
+#include <Adafruit_BME680.h>
+// Change this if you want altitude computed for your location
+#define SEALEVEL_HPA (1013.25f)
+// Try both common I2C addresses
+Adafruit_BME680 bme; // use the default constructor
+bool beginBME680() {
+  // SDA on pin 21 and SCL on pin 22
+  Wire.begin(21, 22);
+  // Try 0x76 first
+  if (bme.begin(0x76, &Wire)) {
+    Serial.println("[BME680] Found at 0x76");
+    return true;
+  }
+  // Then 0x77
+  if (bme.begin(0x77, &Wire)) {
+    Serial.println("[BME680] Found at 0x77");
+    return true;
+  }
+  Serial.println("[BME680] Sensor not found at 0x76 or 0x77. Check wiring/power.");
+  return false;
+}
+void setupBME680() {
+  // Oversampling & filter settings tuned for ~1 Hz updates
+  bme.setTemperatureOversampling(BME680_OS_8X);
+  bme.setHumidityOversampling(BME680_OS_2X);
+  bme.setPressureOversampling(BME680_OS_4X);
+  bme.setIIRFilterSize(BME680_FILTER_SIZE_3);
+  // Enable gas heater: 320°C for 150 ms (typical example)
+  bme.setGasHeater(320, 150);
+}
+void setup() {
+  Serial.begin(115200);
+  while (!Serial) { delay(100); }
+  Serial.println("\n[BOOT] BME680 serial demo (1 Hz)");
+  if (!beginBME680()) {
+    // Stay here so you can read the error
+    while (true) { delay(1000); }
+  }
+  setupBME680();
+}
+void loop() {
+  // Trigger a reading and wait for completion
+  if (!bme.performReading()) {
+    Serial.println("[BME680] Failed to perform reading!");
+    delay(1000);
+    return;
+  }
+  // Values from the Adafruit_BME680 library:
+  float temperatureC = bme.temperature;               // °C
+  float pressureHpa  = bme.pressure / 100.0f;         // Pa -> hPa
+  float humidityPct  = bme.humidity;                  // %
+  float gasOhms      = bme.gas_resistance;            // Ω
+  float altitudeM    = bme.readAltitude(SEALEVEL_HPA);// meters (approx.)
+  // Print nicely
+  Serial.print("T: ");  Serial.print(temperatureC, 2); Serial.print(" °C  | ");
+  Serial.print("RH: "); Serial.print(humidityPct, 1);  Serial.print(" %  | ");
+  Serial.print("P: ");  Serial.print(pressureHpa, 2);  Serial.print(" hPa  | ");
+  Serial.print("Gas: ");Serial.print(gasOhms, 0);      Serial.print(" Ω  | ");
+  Serial.print("Alt: ");Serial.print(altitudeM, 1);    Serial.println(" m");
+  // 1 Hz update
+  delay(1000);
+}
+</code>
+=== 4. Scan and display local WiFi networks ===
+Now let's make sure we can connect to WiFi. Load this WiFi scanner code:
 <code C main.cpp>
@@ Line 179: / Line 270: @@
-=== 3. Advertise on BLE  ===
+=== 6. Web Server ===
+Now let's bring everything together and configure the board to connect to our local WiFi, act as a web server and display a dynamic html page in which it can plot the sensor readings.
+Use this code to build the firmware image:
+<code C main.cpp>
+#include <Arduino.h>
+#include <Wire.h>
+#include <WiFi.h>
+#include <WebServer.h>
+#include <SPIFFS.h>
+#include <ESPmDNS.h>
+#include <Adafruit_BME680.h>
+#define SEALEVEL_HPA (1013.25f)   // adjust for better altitude accuracy
+// ===== WiFi =====
+const char* WIFI_SSID = "YOUR_SSID";
+const char* WIFI_PASS = "YOUR_PASSWORD";
+const char* MDNS_NAME = "sparrow";        // -> http://sparrow.local/
+// ===== Web =====
+WebServer server(80);
+// ===== BME680 =====
+Adafruit_BME680 bme;
+bool haveBME = false;
+// ===== History buffer (5 minutes @ 1 Hz) =====
+static const size_t HISTORY_MAX = 300;
+struct Sample {
+  uint32_t t_ms;
+  float tC;
+  float hPct;
+  float pHpa;
+  float altM;
+};
+Sample hist[HISTORY_MAX];
+size_t histHead = 0;
+size_t histCount = 0;
+void pushSample(const Sample& s) {
+  hist[histHead] = s;
+  histHead = (histHead + 1) % HISTORY_MAX;
+  if (histCount < HISTORY_MAX) histCount++;
+}
+Sample getSampleByAge(size_t iOldToNew) {
+  size_t idx = (histHead + HISTORY_MAX - histCount + iOldToNew) % HISTORY_MAX;
+  return hist[idx];
+}
+// ===== Sensor init and reading =====
+bool beginBME680() {
+  Wire.begin(21, 22); // set custom SDA/SCL here if needed: Wire.begin(SDA, SCL);
+  if (bme.begin(0x76, &Wire)) { Serial.println("[BME680] Found at 0x76"); return true; }
+  if (bme.begin(0x77, &Wire)) { Serial.println("[BME680] Found at 0x77"); return true; }
+  Serial.println("[BME680] Not found at 0x76/0x77");
+  return false;
+}
+void setupBME680() {
+  bme.setTemperatureOversampling(BME680_OS_8X);
+  bme.setHumidityOversampling(BME680_OS_2X);
+  bme.setPressureOversampling(BME680_OS_4X);
+  bme.setIIRFilterSize(BME680_FILTER_SIZE_3);
+  bme.setGasHeater(320, 150); // optional
+}
+bool takeAndStoreSample() {
+  if (!haveBME) return false;
+  if (!bme.performReading()) return false;
+  Sample s;
+  s.t_ms = millis();
+  s.tC   = bme.temperature;
+  s.hPct = bme.humidity;
+  s.pHpa = bme.pressure / 100.0f;
+  s.altM = bme.readAltitude(SEALEVEL_HPA);
+  pushSample(s);
+  return true;
+}
+// ===== HTTP handlers =====
+void handleRoot() {
+  File f = SPIFFS.open("/index.html", "r");
+  if (!f) { server.send(500, "text/plain", "index.html missing"); return; }
+  server.streamFile(f, "text/html");
+  f.close();
+}
+void handleApiSensor() {
+  if (histCount == 0) takeAndStoreSample();
+  Sample s = (histCount == 0) ? Sample{millis(), NAN, NAN, NAN, NAN}
+                              : getSampleByAge(histCount - 1);
+  String json = "{";
+  json += "\"ok\":" + String(haveBME ? "true" : "false");
+  json += ",\"temperature_c\":" + String(isnan(s.tC)?0:s.tC, 2);
+  json += ",\"humidity_pct\":" + String(isnan(s.hPct)?0:s.hPct, 1);
+  json += ",\"pressure_hpa\":" + String(isnan(s.pHpa)?0:s.pHpa, 2);
+  json += ",\"altitude_m\":" + String(isnan(s.altM)?0:s.altM, 1);
+  json += "}";
+  server.send(200, "application/json", json);
+}
+void handleApiHistory() {
+  uint32_t nowms = millis();
+  size_t n = histCount;
+  if (n == 0) { server.send(200, "application/json", "{\"ok\":true,\"n\":0}"); return; }
+  String json;
+  json.reserve(n * 64 + 128);
+  json += "{\"ok\":true,\"n\":" + String(n);
+  // seconds ago array
+  json += ",\"s\":[";
+  for (size_t i = 0; i < n; ++i) {
+    Sample s = getSampleByAge(i);
+    uint32_t secAgo = (nowms - s.t_ms) / 1000;
+    json += String(secAgo);
+    if (i + 1 < n) json += ",";
+  }
+  json += "]";
+  auto appendSeries = [&](const char* key, float Sample::*field, int digits) {
+    json += ",\""; json += key; json += "\":[";
+    for (size_t i = 0; i < n; ++i) {
+      Sample s = getSampleByAge(i);
+      json += String(s.*field, digits);
+      if (i + 1 < n) json += ",";
+    }
+    json += "]";
+  };
+  appendSeries("tc",  &Sample::tC,   2);
+  appendSeries("rh",  &Sample::hPct, 1);
+  appendSeries("p",   &Sample::pHpa, 2);
+  appendSeries("alt", &Sample::altM, 1);
+  json += "}";
+  server.send(200, "application/json", json);
+}
+void handleApiStatus() {
+  bool up = WiFi.status() == WL_CONNECTED;
+  long rssi = up ? WiFi.RSSI() : -127;   // dBm
+  uint32_t uptimeS = millis() / 1000;
+  String json = "{";
+  json += "\"ok\":true";
+  json += ",\"rssi_dbm\":" + String(rssi);
+  json += ",\"uptime_s\":" + String(uptimeS);
+  json += ",\"hostname\":\"" + String(MDNS_NAME) + "\"";
+  json += ",\"ip\":\"" + (up ? WiFi.localIP().toString() : String("")) + "\"";
+  json += "}";
+  server.send(200, "application/json", json);
+}
+void setup() {
+  Serial.begin(115200);
+  while (!Serial) { delay(10); }
+  Serial.println("\n[BOOT] ESP32-C6 BME680 Web Graphs + Status + mDNS");
+  if (!SPIFFS.begin(true)) Serial.println("[SPIFFS] Mount failed");
+  else Serial.println("[SPIFFS] Mounted");
+  // WiFi + mDNS
+  WiFi.mode(WIFI_STA);
+  WiFi.setSleep(false);
+  WiFi.setHostname(MDNS_NAME);
+  WiFi.begin(WIFI_SSID, WIFI_PASS);
+  Serial.printf("[WiFi] Connecting to %s", WIFI_SSID);
+  unsigned long t0 = millis();
+  while (WiFi.status() != WL_CONNECTED && millis() - t0 < 20000) {
+    Serial.print(".");
+    delay(500);
+  }
+  Serial.println();
+  if (WiFi.status() == WL_CONNECTED) {
+    Serial.printf("[WiFi] Connected. IP: %s\n", WiFi.localIP().toString().c_str());
+    if (MDNS.begin(MDNS_NAME)) {
+      MDNS.addService("http", "tcp", 80);
+      Serial.printf("[mDNS] http://%s.local/\n", MDNS_NAME);
+    } else {
+      Serial.println("[mDNS] start failed");
+    }
+  } else {
+    Serial.println("[WiFi] Failed to connect (continuing)");
+  }
+  // Sensor
+  haveBME = beginBME680();
+  if (haveBME) setupBME680();
+  // Prime buffer
+  takeAndStoreSample();
+  // Routes
+  server.on("/",           HTTP_GET, handleRoot);
+  server.on("/api/sensor", HTTP_GET, handleApiSensor);
+  server.on("/api/history",HTTP_GET, handleApiHistory);
+  server.on("/api/status", HTTP_GET, handleApiStatus);
+  server.onNotFound([]() {
+    String path = server.uri();
+    if (path == "/") { handleRoot(); return; }
+    if (!SPIFFS.exists(path)) { server.send(404, "text/plain", "Not found"); return; }
+    String ct = "text/plain";
+    if      (path.endsWith(".html")) ct = "text/html";
+    else if (path.endsWith(".css"))  ct = "text/css";
+    else if (path.endsWith(".js"))   ct = "application/javascript";
+    File f = SPIFFS.open(path, "r"); server.streamFile(f, ct); f.close();
+  });
+  server.begin();
+  Serial.println("[HTTP] Server started");
+  if (WiFi.status() == WL_CONNECTED)
+    Serial.println("[HTTP] Open: http://" + WiFi.localIP().toString() + "/  or  http://sparrow.local/");
+}
+void loop() {
+  server.handleClient();
+  // 1 Hz sampling
+  static uint32_t lastSample = 0;
+  uint32_t now = millis();
+  if (now - lastSample >= 1000) {
+    lastSample = now;
+    takeAndStoreSample();
+  }
+  delay(2);
+}
+</code>
+The web page that the node will serve needs to be stored in ESP32's internal memory. It has a limited amount of internal Flash (8MB) which is enough to store a tiny web page. Create a new folder in the root of your project and mane it "data". In it, create a file called index.html and paste the contents below:
+<code html index.html>
+<!doctype html>
+<html lang="en" data-theme="light">
+<head>
+  <meta charset="utf-8"/>
+  <title>BME680 Dashboard</title>
+  <meta name="viewport" content="width=device-width, initial-scale=1"/>
+  <style>
+    :root {
+      --bg:#ffffff; --fg:#222; --muted:#777; --card:#f7f7f7; --axis:#00000066; --grid:#00000012; --line:#0b6;
+    }
+    [data-theme="dark"] {
+      --bg:#0f1115; --fg:#eaeef2; --muted:#9aa4b2; --card:#171a21; --axis:#ffffff66; --grid:#ffffff13; --line:#38bdf8;
+    }
+    html,body { height:100%; }
+    body { background: var(--bg); color: var(--fg);
+           font-family: system-ui,-apple-system,Segoe UI,Roboto,sans-serif; margin: 16px; }
+    h1 { margin: 0 0 8px 0; }
+    .row { display:flex; gap:16px; flex-wrap:wrap; align-items:baseline; }
+    .metric { font-size: 1.4rem; }
+    .label { color: var(--muted); font-size:.9rem; }
+    .grid { display:grid; grid-template-columns: repeat(2, minmax(280px,1fr)); gap:16px; }
+    .card { background: var(--card); border-radius: 12px; padding: 12px; box-shadow: 0 1px 3px rgba(0,0,0,.06); }
+    .title { color: var(--muted); margin-bottom: 6px; }
+    canvas { width:100%; height:200px; display:block; }
+    .ts { color: var(--muted); margin-top: 8px; font-size:.9rem; }
+    @media (max-width: 700px) { .grid { grid-template-columns: 1fr; } }
+    /* Toggle + status pill */
+    .topbar { display:flex; justify-content:space-between; align-items:center; margin-bottom:8px; gap:12px; }
+    .toggle { cursor:pointer; padding:6px 10px; border-radius:10px; background:var(--card); border:1px solid #00000010; }
+    .pill { position: sticky; top: 8px; align-self: start; padding:6px 10px; border-radius:999px;
+            background:var(--card); border:1px solid #00000010; color:var(--fg); font-size:.9rem; }
+    .pill a { color: inherit; text-decoration: none; border-bottom:1px dotted var(--muted); }
+  </style>
+</head>
+<body>
+  <div class="topbar">
+    <h1>BME680 Dashboard (5 min)</h1>
+    <div class="toggle" id="themeToggle">🌙 Dark mode</div>
+  </div>
+  <div class="row" style="margin-bottom:8px;">
+    <div class="pill" id="status">Wi-Fi: -- dBm · Uptime: --:--:-- · <a href="http://sparrow.local" target="_blank" rel="noreferrer">sparrow.local</a></div>
+  </div>
+  <div class="row">
+    <div><span class="label">Temperature</span> <span id="t" class="metric">--</span></div>
+    <div><span class="label">Humidity</span> <span id="h" class="metric">--</span></div>
+    <div><span class="label">Pressure</span> <span id="p" class="metric">--</span></div>
+    <div><span class="label">Altitude</span> <span id="a" class="metric">--</span></div>
+  </div>
+  <div class="grid" style="margin-top:12px;">
+    <div class="card"><div class="title">Temperature (°C)</div><canvas id="ct"></canvas></div>
+    <div class="card"><div class="title">Humidity (%)</div><canvas id="ch"></canvas></div>
+    <div class="card"><div class="title">Pressure (hPa)</div><canvas id="cp"></canvas></div>
+    <div class="card"><div class="title">Altitude (m)</div><canvas id="ca"></canvas></div>
+  </div>
+  <div class="ts" id="ts">Waiting for data…</div>
+<script>
+const secsWindow = 300; // 5 minutes
+function $(id){ return document.getElementById(id); }
+// ---- Theme toggle (persisted) ----
+(function initTheme(){
+  const saved = localStorage.getItem('theme') || 'light';
+  document.documentElement.setAttribute('data-theme', saved);
+  $('themeToggle').textContent = saved === 'dark' ? '☀️ Light mode' : '🌙 Dark mode';
+  $('themeToggle').addEventListener('click', () => {
+    const cur = document.documentElement.getAttribute('data-theme') || 'light';
+    const next = cur === 'dark' ? 'light' : 'dark';
+    document.documentElement.setAttribute('data-theme', next);
+    localStorage.setItem('theme', next);
+    $('themeToggle').textContent = next === 'dark' ? '☀️ Light mode' : '🌙 Dark mode';
+  });
+})();
+// ---- Chart helpers ----
+function decimalsForRange(range){
+  if (!isFinite(range) || range <= 0) return 1;
+  if (range < 2) return 2;
+  if (range < 20) return 1;
+  return 0;
+}
+function drawSeries(canvas, secondsAgo, values, color) {
+  const dpr = window.devicePixelRatio || 1;
+  const padL = 48 * dpr, padR = 8 * dpr, padT = 8 * dpr, padB = 18 * dpr;
+  const ctx = canvas.getContext('2d');
+  const w = canvas.width  = Math.max(10, canvas.clientWidth  * dpr);
+  const h = canvas.height = Math.max(10, canvas.clientHeight * dpr);
+  ctx.clearRect(0,0,w,h);
+  if (!values || values.length < 2) return;
+  const clean = values.filter(v => isFinite(v));
+  if (clean.length < 2) return;
+  let vMin = Math.min(...clean);
+  let vMax = Math.max(...clean);
+  if (vMin === vMax) { vMin -= 0.5; vMax += 0.5; }
+  const pad = (vMax - vMin) * 0.08;
+  const yMin = vMin - pad;
+  const yMax = vMax + pad;
+  const yRange = yMax - yMin;
+  const yDec = decimalsForRange(yRange);
+  const plotW = w - padL - padR;
+  const plotH = h - padT - padB;
+  // Axes + grid
+  ctx.strokeStyle = getComputedStyle(document.documentElement).getPropertyValue('--axis').trim();
+  ctx.lineWidth = 1 * dpr;
+  ctx.beginPath(); ctx.moveTo(padL, padT); ctx.lineTo(padL, h - padB); ctx.stroke();
+  ctx.beginPath(); ctx.moveTo(padL, h - padB); ctx.lineTo(w - padR, h - padB); ctx.stroke();
+  ctx.strokeStyle = getComputedStyle(document.documentElement).getPropertyValue('--grid').trim();
+  ctx.fillStyle = getComputedStyle(document.documentElement).getPropertyValue('--axis').trim();
+  ctx.textAlign = 'right'; ctx.textBaseline = 'middle';
+  ctx.font = `${12*dpr}px system-ui,-apple-system,Segoe UI,Roboto,sans-serif`;
+  for (let i = 0; i <= 5; i++) {
+    const frac = i / 5;
+    const yVal = yMax - yRange * frac;
+    const y = padT + plotH * frac;
+    ctx.beginPath(); ctx.moveTo(padL, y); ctx.lineTo(w - padR, y); ctx.stroke();
+    ctx.fillText(yVal.toFixed(yDec), padL - 6*dpr, y);
+  }
+  const xForSec = s => padL + plotW * (1 - Math.min(s, secsWindow) / secsWindow);
+  const yForVal = v => padT + plotH * ((yMax - v) / yRange);
+  ctx.strokeStyle = color || getComputedStyle(document.documentElement).getPropertyValue('--line').trim();
+  ctx.lineWidth = Math.max(1, 1.5 * dpr);
+  ctx.beginPath();
+  for (let i = 0; i < values.length; i++) {
+    const x = xForSec(secondsAgo[i]);
+    const y = yForVal(values[i]);
+    if (i === 0) ctx.moveTo(x, y); else ctx.lineTo(x, y);
+  }
+  ctx.stroke();
+  // X labels
+  ctx.fillStyle = getComputedStyle(document.documentElement).getPropertyValue('--axis').trim();
+  ctx.textAlign = 'center'; ctx.textBaseline = 'top';
+  const xLabels = [{s:300, txt:'-5m'}, {s:150, txt:'-2.5m'}, {s:5, txt:'now'}];
+  xLabels.forEach(l=>{
+    const x = xForSec(l.s);
+    ctx.fillText(l.txt, x, h - padB + 4*dpr);
+  });
+}
+// ---- Data refresh ----
+async function refreshHistory() {
+  try {
+    const r = await fetch('/api/history', {cache:'no-store'});
+    const j = await r.json();
+    if (!j.ok) { $('ts').textContent = 'No data'; return; }
+    const n = j.n || 0;
+    if (n>0) {
+      $('t').textContent = j.tc[n-1].toFixed(2)+' °C';
+      $('h').textContent = j.rh[n-1].toFixed(1)+' %';
+      $('p').textContent = j.p[n-1].toFixed(2)+' hPa';
+      $('a').textContent = j.alt[n-1].toFixed(1)+' m';
+    }
+    drawSeries($('ct'), j.s, j.tc, '#e4572e');
+    drawSeries($('ch'), j.s, j.rh, '#17bebb');
+    drawSeries($('cp'), j.s, j.p,  '#4a7');
+    drawSeries($('ca'), j.s, j.alt,'#999');
+    $('ts').textContent = 'Updated: ' + new Date().toLocaleTimeString();
+  } catch {
+    $('ts').textContent = 'Fetch error';
+  }
+}
+function fmtUptime(sec){
+  const h = Math.floor(sec/3600);
+  const m = Math.floor((sec%3600)/60);
+  const s = sec%60;
+  const pad = n => n.toString().padStart(2,'0');
+  return `${pad(h)}:${pad(m)}:${pad(s)}`;
+}
+async function refreshStatus(){
+  try {
+    const r = await fetch('/api/status', {cache:'no-store'});
+    const j = await r.json();
+    const rssi = (j && Number.isFinite(j.rssi_dbm)) ? `${j.rssi_dbm} dBm` : '-- dBm';
+    const up   = (j && Number.isFinite(j.uptime_s)) ? fmtUptime(j.uptime_s) : '--:--:--';
+    $('status').innerHTML = `Wi-Fi: ${rssi} · Uptime: ${up} · <a href="http://${j.hostname||'sparrow'}.local" target="_blank" rel="noreferrer">${j.hostname||'sparrow'}.local</a>`;
+  } catch {
+    $('status').textContent = 'Wi-Fi: -- dBm · Uptime: --:--:-- · sparrow.local';
+  }
+}
+refreshHistory();
+refreshStatus();
+setInterval(refreshHistory, 2000);
+setInterval(refreshStatus, 5000);
+</script>
+</body>
+</html>
+</code>
+<note warning>In order to upload the contents of the /data folder, you will need to run "Upload Filesystem Image".
+</note>
+=== 6. Advertise on BLE  ===
 Build the example below, which advertises the board on BLE. Install on your phone an app that scans nearby Bluetooth devices, such as [[https://play.google.com/store/apps/details?id=no.nordicsemi.android.mcp&hl=en&pli=1| nRF Connect]]. Check if your device is in the list.