wip: start access point if wifi fails

noisemeter-device/noisemeter-device.ino

@@ -38,6 +38,8 @@ static Storage Creds;
 // Uncomment these to disable WiFi and/or data upload
 //#define UPLOAD_DISABLED
 
+constexpr auto WIFI_CONNECT_TIMEOUT_MS = 20 * 1000;
+
 const unsigned long UPLOAD_INTERVAL_SEC = 60 * 5;  // Upload every 5 mins
 // const unsigned long UPLOAD_INTERVAL_SEC = 30;  // Upload every 30 secs
 
@@ -99,6 +101,10 @@ double Leq_dB = 0;
 static std::forward_list<DataPacket> packets;
 static Timestamp lastUpload = Timestamp::invalidTimestamp();
 
+[[noreturn]]
+static void enterAccessPointMode();
+static int tryWifiConnection();
+
 /**
  * Initialization routine.
  */
@@ -130,40 +136,28 @@ void setup() {
   packets.emplace_front();
 
 #ifndef UPLOAD_DISABLED
-  // Run the access point if it is requested or if there are no valid credentials.
-  bool resetPressed = !digitalRead(PIN_BUTTON);
-  if (resetPressed || !Creds.valid() || Creds.get(Storage::Entry::SSID).isEmpty()) {
-    AccessPoint ap (saveNetworkCreds);
+  bool isAPNeeded = false;
 
+  if (!digitalRead(PIN_BUTTON) || !Creds.valid()) {
     SERIAL.print("Erasing stored credentials...");
     Creds.clear();
     SERIAL.println(" done.");
 
-    ap.run(); // does not return
+    isAPNeeded = true;
+  } else if (tryWifiConnection() < 0 || Timestamp::synchronize() < 0) {
+    isAPNeeded = true;
   }
 
-  // Valid credentials: Next step would be to connect to the network.
-  const auto ssid = Creds.get(Storage::Entry::SSID);
-
-  SERIAL.print("Ready to connect to ");
-  SERIAL.println(ssid);
+  // Run the access point if it is requested or if there are no valid credentials.
+  if (isAPNeeded) {
+    enterAccessPointMode(); // Does not return
+  }
 
-  WiFi.mode(WIFI_STA);
-  WiFi.begin(ssid.c_str(), Creds.get(Storage::Entry::Passkey).c_str());
+  lastUpload = Timestamp();
 
-  // wait for WiFi connection
-  SERIAL.print("Waiting for WiFi to connect...");
-  while (WiFi.status() != WL_CONNECTED) {
-    SERIAL.print(".");
-    delay(500);
-  }
-  SERIAL.println("\nConnected to the WiFi network");
+  SERIAL.println("Connected to the WiFi network.");
   SERIAL.print("Local ESP32 IP: ");
   SERIAL.println(WiFi.localIP());
-
-  SERIAL.println("Waiting for NTP time sync...");
-  Timestamp::synchronize();
-  lastUpload = Timestamp();
   SERIAL.print("Current time: ");
   SERIAL.println(lastUpload);
 #endif // !UPLOAD_DISABLED
@@ -237,7 +231,7 @@ void saveNetworkCreds(WebServer& httpServer) {
     UUID uuid; // generates random UUID
 
     // Confirm that the given credentials will fit in the allocated EEPROM space.
-    if (Creds.canStore(ssid) && Creds.canStore(psk)) {
+    if (!ssid.isEmpty() && Creds.canStore(ssid) && Creds.canStore(psk)) {
       Creds.set(Storage::Entry::SSID, ssid);
       Creds.set(Storage::Entry::Passkey, psk);
       Creds.set(Storage::Entry::UUID, uuid.toCharArray());
@@ -256,6 +250,41 @@ void saveNetworkCreds(WebServer& httpServer) {
   SERIAL.println("Error: Invalid network credentials!");
 }
 
+void enterAccessPointMode()
+{
+    AccessPoint ap (saveNetworkCreds);
+
+    SERIAL.print("Erasing stored credentials...");
+    Creds.clear();
+    SERIAL.println(" done.");
+
+    ap.run(); // does not return
+}
+
+int tryWifiConnection()
+{
+  const auto ssid = Creds.get(Storage::Entry::SSID);
+
+  SERIAL.print("Ready to connect to ");
+  SERIAL.println(ssid);
+
+  WiFi.mode(WIFI_STA);
+  WiFi.begin(ssid.c_str(), Creds.get(Storage::Entry::Passkey).c_str());
+
+  // wait for WiFi connection
+  SERIAL.print("Waiting for WiFi to connect...");
+  auto start = millis();
+  bool connected;
+
+  do {
+    connected = WiFi.status() != WL_CONNECTED;
+    SERIAL.print(".");
+    delay(500);
+  } while (!connected && millis() - start < WIFI_CONNECT_TIMEOUT_MS);
+
+  return connected ? 0 : -1;
+}
+
 String createJSONPayload(String deviceId, const DataPacket& dp)
 {
 #ifdef BUILD_PLATFORMIO

noisemeter-device/timestamp.h

@@ -7,36 +7,14 @@
 class Timestamp
 {
 public:
-    Timestamp(std::time_t tm_ = std::time(nullptr)):
-        tm(tm_) {}
+    Timestamp(std::time_t tm_ = std::time(nullptr));
 
-    bool valid() const noexcept {
-        return tm >= 8 * 3600 * 2;
-    }
+    bool valid() const noexcept;
+    operator String() const noexcept;
+    double secondsBetween(Timestamp ts) const noexcept;
 
-    operator String() const noexcept {
-        char tsbuf[32];
-        const auto timeinfo = std::gmtime(&tm);
-        const auto success = std::strftime(tsbuf, sizeof(tsbuf), "%c", timeinfo) > 0;
-
-        return success ? tsbuf : "(error)";
-    }
-
-    auto secondsBetween(Timestamp ts) const noexcept {
-        return std::difftime(ts.tm, tm);
-    }
-
-    static void synchronize() {
-        configTime(0, 0, "pool.ntp.org");
-
-        do {
-            delay(1000);
-        } while (!Timestamp().valid());
-    }
-
-    static Timestamp invalidTimestamp() {
-        return Timestamp(0);
-    }
+    static int synchronize();
+    static Timestamp invalidTimestamp();
 
 private:
     std::time_t tm;