How to make nodemcu auto connect strong wifi signal [closed] - arduino

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To many wifi but need to connect strong signal (dynamic switch between wifi look like mobilephone)

Answer 1

Automatically Connecting to the strongest network
Scan networks
int8_t scanNetworks(bool async, bool show_hidden, uint8 channel, uint8* ssid);
You can either continuously scan for available networks or
do a periodic check using the scanNetworks function which returns the number of networks found.
scanNetworks will return the number (8-bit integer) of networks found.
By default async flag is set to false so your program will halt while nodemcu is
scaning networks.
You can set it to true so your program keeps running while networks are being scanned.
Don't worry about other arguments, they are set to default value.
You can change them if you want just by passing values for those as well.
Remember that while you are scanning for networks your Wifi mode is switched to station
so if you want to continuously scan networks while you are in access point mode,
your station will be turned off. And you will have to restart the access point
after scan is completed.
While scan is running the scanNetworks function will return WIFI_SCAN_RUNNING
You can process the results if
(WiFi.scanNetworks() != WIFI_SCAN_RUNNING)
Processing the results of WiFi Scan
int_32t WiFi.RSSI(unit_8t i); // returns the network strength of ith network
String WiFi.SSID(uint8_t i); // returns the ssid of ith network
Results are indexed in descending order of strength,
so the 0th result has the highest strength, and nth result has the least strength
Once the scan is complete, provided that you know the passwords of the available networks
you can directly connect to the 0th result by writing
WiFi.begin(WiFi.SSID(0), password);
But its always a good idea to check whether you know that network.
You can easily do that by having a list of the known (trusted) networks.
and comparing every result's ssid to every member of the list.
If they match, then you can start the connection.
char knownNetworks [][] =
{
"Network1",
"Network2",
};
#define KNOWN_NETWORKS 2
int8_t networkResult = WiFi.scanNetworks();
for(int i = 0; i < KNOWN_NETWORKS; i++)
for(int j = 0; j < scanResult; j++)
if(strcpy(knownNetworks[i], WiFi.SSID(j) == 0)
WiFi.begin(knownNetworks[i], password);
I hope this was helpful!
If You have any questions, I would be happy to help.

Answer 2

Please try this
// #include WiFi Library
#include <ESP8266WiFi.h>
/* Serial Baud Rate */
#define SERIAL_BAUD 9600
/* Delay paramter for connection. */
#define WIFI_DELAY 500
/* Max SSID octets. */
#define MAX_SSID_LEN 32
/* Wait this much until device gets IP. */
#define MAX_CONNECT_TIME 30000
/* SSID that to be stored to connect. */
char ssid[MAX_SSID_LEN] = "";
/* Scan available networks and sort them in order to their signal strength. */
void scanAndSort() {
memset(ssid, 0, MAX_SSID_LEN);
int n = WiFi.scanNetworks();
Serial.println("Scan complete!");
if (n == 0) {
Serial.println("No networks available.");
} else {
Serial.print(n);
Serial.println(" networks discovered.");
int indices[n];
for (int i = 0; i < n; i++) {
indices[i] = i;
}
for (int i = 0; i < n; i++) {
for (int j = i + 1; j < n; j++) {
if (WiFi.RSSI(indices[j]) > WiFi.RSSI(indices[i])) {
std::swap(indices[i], indices[j]);
}
}
}
for (int i = 0; i < n; ++i) {
Serial.println("The strongest open network is:");
Serial.print(WiFi.SSID(indices[i]));
Serial.print(" ");
Serial.print(WiFi.RSSI(indices[i]));
Serial.print(" ");
Serial.print(WiFi.encryptionType(indices[i]));
Serial.println();
if(WiFi.encryptionType(indices[i]) == ENC_TYPE_NONE) {
memset(ssid, 0, MAX_SSID_LEN);
strncpy(ssid, WiFi.SSID(indices[i]).c_str(), MAX_SSID_LEN);
break;
}
}
}
}
void setup() {
// Scan, Sort, and Connect to WiFi
Serial.begin(SERIAL_BAUD);
Serial.println("Scanning for open networks...");
if(WiFi.status() != WL_CONNECTED) {
/* Clear previous modes. */
WiFi.softAPdisconnect();
WiFi.disconnect();
WiFi.mode(WIFI_STA);
delay(WIFI_DELAY);
/* Scan for networks to find open guy. */
scanAndSort();
delay(WIFI_DELAY);
/* Global ssid param need to be filled to connect. */
if(strlen(ssid) > 0) {
Serial.print("Connecting to ");
Serial.println(ssid);
/* No pass for WiFi. We are looking for non-encrypteds. */
WiFi.begin(ssid);
unsigned short try_cnt = 0;
/* Wait until WiFi connection but do not exceed MAX_CONNECT_TIME */
while (WiFi.status() != WL_CONNECTED && try_cnt < MAX_CONNECT_TIME / WIFI_DELAY) {
delay(WIFI_DELAY);
Serial.print(".");
try_cnt++;
}
if(WiFi.status() == WL_CONNECTED) {
Serial.println("");
Serial.println("Connection Successful!");
Serial.println("Your device IP address is ");
Serial.println(WiFi.localIP());
} else {
Serial.println("Connection FAILED");
}
} else {
Serial.println("No open networks available. :-(");
}
}
}
void loop () {
}