improved wifi management

- Possibility to create an access point on the ESP32
- Possibility to make the ESP32 try to connect to multiple access points

ESP32/vehicle-monitor.cpp

@@ -2,6 +2,7 @@
 #include "IDECompat.h"
 
 #include <WiFi.h>
+#include <WiFiMulti.h>
 #include <FS.h>
 #include <SPIFFS.h>
 #include <ESPAsyncWebServer.h>
@@ -24,6 +25,11 @@ const float wheelCircumferenceMeters = wheelDiameterInches * 0.0254f * 3.1415f /
 int16_t batteryVoltage = -1; // in mV
 int16_t batteryCurrent = -1; // in mV
 
+WiFiMulti wifiMulti;
+wl_status_t wifi_STA_status = WL_NO_SHIELD;
+unsigned long wifiConnexionBegin = 0;
+const unsigned long retryWifiConnexionDelay = 60000; // in milliseconds
+
 volatile bool debugLedState = true;
 
 volatile bool speedSensorState = false;
@@ -81,6 +87,25 @@ float getSpeed()
 	return speed;
 }
 
+void connectWifi()
+{
+	wifiMulti = WiFiMulti();
+
+	const int numSSIDs = sizeof(wifi_STA_credentials)/sizeof(wifi_STA_credentials[0]);
+	if(numSSIDs > 0)
+	{
+		Serial.println("Connecting to wifi...");
+
+		for(int idx = 0; idx < numSSIDs; ++idx)
+		{
+			wifiMulti.addAP(wifi_STA_credentials[idx].SSID, wifi_STA_credentials[idx].password);
+		}
+
+		wifiConnexionBegin = millis();
+		wifiMulti.run();
+	}
+}
+
 void setup()
 {
 	pinMode(speedSensorPin, INPUT_PULLUP);
@@ -96,17 +121,23 @@ void setup()
 		return;
 	}
 
-	// Connect to Wi-Fi
-	WiFi.begin(wifi_ssid, wifi_password);
-	while (WiFi.status() != WL_CONNECTED)
+	// Set WiFi mode to both AccessPoint and Station
+	WiFi.mode(WIFI_AP_STA);
+
+	// Create the WiFi Access Point
+	if(wifi_AP_ssid != nullptr)
 	{
-		delay(1000);
-		Serial.println("Connecting to Wifi...");
+		Serial.println("Creating wifi access point...");
+		WiFi.softAP(wifi_AP_ssid, wifi_AP_password);
+
+		Serial.print("Wifi access point created, SSID=");
+		Serial.print(wifi_AP_ssid);
+		Serial.print(", IP=");
+		Serial.println(WiFi.softAPIP());
 	}
 
-	// Print ESP Local IP Address
-	Serial.print("Wifi connected, ip=");
-	Serial.println(WiFi.localIP());
+	// Also connect as a station (if the configured remote access point is in range)
+	connectWifi();
 
 	server.on("/api/status", HTTP_GET, [](AsyncWebServerRequest *request){
 		int v = batteryVoltage;
@@ -131,6 +162,45 @@ void setup()
 
 void loop()
 {
+	wl_status_t newWifiStatus = WiFi.status();
+	if(newWifiStatus != wifi_STA_status)
+	{
+		if(newWifiStatus == WL_CONNECTED)
+		{
+			Serial.print("Connected to wifi (");
+			Serial.print(WiFi.SSID().c_str());
+			Serial.print("), ip=");
+			Serial.println(WiFi.localIP());
+		}
+		else if(newWifiStatus == WL_DISCONNECTED)
+		{
+			char codeStr[16];
+			sprintf(codeStr, "%d", (int)newWifiStatus);
+			Serial.print("Lost wifi connexion (");
+			Serial.print(codeStr);
+			Serial.println(")");
+
+			connectWifi();
+		}
+		else
+		{
+			char codeStr[16];
+			sprintf(codeStr, "%d", (int)newWifiStatus);
+			Serial.print("Wifi state: ");
+			Serial.println(codeStr);
+		}
+
+		wifi_STA_status = newWifiStatus;
+	}
+
+	if(wifi_STA_status != WL_CONNECTED)
+	{
+		unsigned long now = millis();
+		unsigned long elapsed = now > wifiConnexionBegin ? now - wifiConnexionBegin : (4294967295 - wifiConnexionBegin) + now;
+		if(elapsed > retryWifiConnexionDelay)
+			connectWifi();
+	}
+
 	const int numSamples = 100;
 
 	float averageV = 0.0f;

ESP32/wifi-credentials.h.template

@@ -1,7 +1,22 @@
 // To avoid saving your wifi credentials in the git repository, wifi-credentials.h.template is ignored by git
 
 // Copy this file and name it wifi-credentials.h
-// Then edit your wifi SSID and password
+// Then edit your wifi configuration
 
-const char* wifi_ssid = "REPLACE_WITH_YOUR_SSID";
-const char* wifi_password = "REPLACE_WITH_YOUR_PASSWORD";
+struct WifiCredentials
+{
+	const char* SSID;
+	const char* password;
+};
+
+// Station config: for making the ESP32 connect to an existing remote access point
+// You can add one or more SSID/password pairs here
+// To disable station mode, add a single entry { NULL, NULL }
+WifiCredentials wifi_STA_credentials[] = {
+	{ "REPLACE_WITH_YOUR_SSID", "REPLACE_WITH_YOUR_PASSWORD" }
+};
+
+// Access point config: for turning the ESP32 into an access point (the ESP32 can work in both modes at the same time)
+// Note that if you connect a smartphone to this AP, it will detect it has no internet access, and then won't send requests to it (which will result in a timeout). A workaround is to turn off mobile data to force the phone use the access point (but then you effectively don't have internet on the phone). A more practical setup is to create an access point on your phone, and have the ESP32 connect to it (in "station" mode)
+const char* wifi_AP_ssid = "REPLACE_WITH_YOUR_SSID"; // set to NULL to disable access point mode
+const char* wifi_AP_password = "REPLACE_WITH_YOUR_PASSWORD"; // set to NULL for an open access point (not recommended)