This lightweight Arduino script helps your ESP automatically connect to the strongest available WiFi and seamlessly handle reconnections when needed.
- Automatically scans and connects to the strongest WiFi signal matching a predefined SSID.
- Non-blocking WiFi management to ensure smooth operation.
- Dynamic Reconnect Handling: If the connection drops, it intelligently attempts to reconnect.
- Power-Saving Mechanism / wifi pollution stopping: WiFi is temporarily disabled if no connection is possible.
- Simple and clearly written so that even beginners (like me) can understand how it works.
- The ESP scans for available networks.
📝 code
void scanWiFiNetwork() {
Serial.println(F(""));
Serial.printf("Start scanning for SSID %s\n", WIFI_SSID);
WiFi.scanNetworks(true); // WiFi.scanNetworks will return the number of networks found
}
- It will then select the strongest RSSI (signal strength) for the given SSID and connetet to it
📝 code
void connectToStrongestWiFi() {
int i_strongest = -1;
int32_t rssi_strongest = -100;
int16_t WiFiScanResult = WiFi.scanComplete();
Serial.println(F(""));
if (WiFiScanResult < 0) {
Serial.println(F("No networks found!"));
} else {
Serial.printf("%d networks found:\n", WiFiScanResult);
for (int i = 0; i < WiFiScanResult; ++i) {
Serial.printf("%d: BSSID: %s %2ddBm, %3d%% %9s %s\n",
i,
WiFi.BSSIDstr(i).c_str(),
WiFi.RSSI(i),
constrain(2 * (WiFi.RSSI(i) + 100), 0, 100),
(WiFi.encryptionType(i) == WIFI_AUTH_OPEN) ? "open" : "encrypted",
WiFi.SSID(i).c_str());
if (strcmp(WIFI_SSID, WiFi.SSID(i).c_str()) == 0 && (WiFi.RSSI(i)) > rssi_strongest) {
rssi_strongest = WiFi.RSSI(i);
i_strongest = i;
}
}
}
if (i_strongest > -1) {
Serial.printf("Connecting to strongest WiFi signal at No. %d. \n", i_strongest);
WiFi.begin(WIFI_SSID, WIFI_PASSWORD, 0, WiFi.BSSID(i_strongest));
} else {
Serial.printf("No network with SSID %s found!\n", WIFI_SSID);
}
}
- If the connection is lost, it switches off the WiFi temporarily and tries to reconnect within a retry window.
📝 code
void handelWiFi() {
if (WiFiconnected && WiFi.localIP() == IPAddress(0, 0, 0, 0)) {
WiFiconnected = false;
Serial.println(F("............................WiFi Disconnected"));
}
if (!WiFiconnected && !WiFiOff && WiFiconnecting_count == 0) {
Serial.println(F("Switching WiFi Off, no WiFi available"));
WiFi.disconnect(true);
WiFi.mode(WIFI_OFF);
delay(1);
WiFiOff = true;
WiFiOff_count = WIFIOFF_COUNT_VALUE;
}
if (WiFiOff) {
--WiFiOff_count;
}
if (WiFiOff && WiFiOff_count == 0) {
Serial.println(F("Try to reconnect"));
WiFi.mode(WIFI_STA);
scanWiFiNetwork();
WiFiOff = false;
WiFiconnecting_count = WIFICONNECTING_COUNT_VALUE;
}
if (WiFiscandone) { // WiFiscandone kommt über WiFiEvent
connectToStrongestWiFi();
WiFi.scanDelete();
WiFiscandone = false;
}
if (!WiFiconnected && WiFiconnecting_count > 0) {
--WiFiconnecting_count;
}
}
- It uses asynchronous callbacks (WiFi.onEvent/WiFiEventHandler that work non-blocking to improve efficiency.
📝 ESP32 code
WiFi.onEvent(onWifiConnect, WiFiEvent_t::ARDUINO_EVENT_WIFI_STA_GOT_IP);
// WiFi.onEvent(onWifiDisconnect, WiFiEvent_t::ARDUINO_EVENT_WIFI_STA_DISCONNECTED); /does not work propper with ESP32
WiFi.onEvent(onWifiScandone, WiFiEvent_t::ARDUINO_EVENT_WIFI_SCAN_DONE);
📝 ESP8266 code
WiFiEventHandler wifiConnectHandler;
WiFiEventHandler wifiDisconnectHandler;
.
.
.
wifiConnectHandler = WiFi.onStationModeGotIP(onWifiConnect);
wifiDisconnectHandler = WiFi.onStationModeDisconnected(onWifiDisconnect);
.
.
.
void onWifiConnect(const WiFiEventStationModeGotIP& event) {
}
void onWifiDisconnect(const WiFiEventStationModeDisconnected& event) {
}
- Periodically logs WiFi state, signal strength, and IP address.
- Helps with debugging and monitoring.
- Easy to integrate custom functions.
📝 example
Start scanning for SSID Test
Scanning WiFi......
15 networks found:
0: BSSID: 00:11:6B:74:94:61 -77dBm, 46% encrypted Test
1: BSSID: 80:1F:02:AE:43:D8 -93dBm, 14% encrypted Test
2: BSSID: 80:1F:02:AE:41:48 -78dBm, 44% encrypted Test
3: BSSID: 80:1F:02:36:31:98 -80dBm, 40% encrypted Test
4: BSSID: 9C:A2:F4:63:65:60 -45dBm, 100% encrypted PG-WLAN
5: BSSID: 06:0B:BD:5A:DB:5D -17dBm, 100% encrypted Test
6: BSSID: 00:11:6B:74:94:2B -91dBm, 18% encrypted Test
7: BSSID: 80:1F:02:36:3A:98 -63dBm, 74% encrypted Test
8: BSSID: 00:11:6B:74:94:79 -82dBm, 36% encrypted der-hotspot
9: BSSID: 80:1F:02:36:31:C8 -71dBm, 58% encrypted Test
10: BSSID: 32:E5:EE:AD:C4:E4 -88dBm, 24% encrypted AndroidAP
11: BSSID: 80:1F:02:36:39:E0 -86dBm, 28% encrypted Test
12: BSSID: 80:1F:02:AE:41:30 -80dBm, 40% encrypted Test
13: BSSID: 80:1F:02:AE:43:F0 -81dBm, 38% encrypted Test
14: BSSID: 00:11:6B:74:94:55 -80dBm, 40% encrypted Test
Connecting to strongest WiFi signal at No. 5.
Connecting WiFi....................................WiFi Connected
.192.168.206.105
WiFiconnected: 1
WiFi-OFF: 0
WiFi-OFF_count: 0
WiFi-Connecting_count: 0
Local IP: 192.168.206.105
WiFi-RSSI: -22
Measurement_count: 59
___________________________
WiFiconnected: 1
WiFi-OFF: 0
WiFi-OFF_count: 0
WiFi-Connecting_count: 0
Local IP: 192.168.206.105
WiFi-RSSI: -24
Measurement_count: 58
___________________________
WiFiconnected: 1
WiFi-OFF: 0
WiFi-OFF_count: 0
WiFi-Connecting_count: 0
Local IP: 192.168.206.105
WiFi-RSSI: -23
Measurement_count: 57
___________________________
- Just change the "defines" from one of the scripts to suit your needs.
📝 code
//=======Defines
#define WIFI_SSID "Test"
#define WIFI_PASSWORD "Password1"
#define WIFIOFF_COUNT_VALUE 90 // Counter for how long WiFi remains off before attempting a reconnection
#define WIFICONNECTING_COUNT_VALUE 10 // Counter for how long WiFi should attempt to connect before being disabled again
#define OTAHOSTNAME "ESP32-WiFi"
#define WiFiHOSTNAME "Test-ESP32"
#define MEASUREMENT_COUNT_VALUE 60 // Multiplier for Heartbeat
#define HEARTBEATINTERVAL_VALUE 1000 // Milliseconds for a Heartbeat
- Flash the script to an ESP8266 / ESP32 device.
