ESP32 Wi-Fi search and connect to saved

wifi_select.ino

#include <WiFi.h>
#include <Preferences.h>
#include <esp_task_wdt.h>

#define CMDPROMPT "ESP32> "
#define TIMEOUT 10000

// cmd line vars
char cmdBuffer[32];
int cmdBufferPosition = 0;
char cmdByte;
int cmdStatus = 0;
int echoInput = 1;
char command[32];
char argument1[32];
char argument2[32];

int wifiCount = 0;
bool connected = false;
bool countdown = false;

Preferences preferences;
String ssid;
String password;

void wifiScan(void);

void setup() { 
    Serial.begin(9600);
    
    preferences.begin("wifi", false);
    
    Serial.println("Booting..");
    WiFi.mode(WIFI_STA);
    WiFi.disconnect();
    delay(100);   

    ssid = preferences.getString("ssid", "");
    password = preferences.getString("password", "");
    
    if (ssid == "") {
        Serial.println("No network saved");
        wifiScan();
    } else {
        countdown = true;
        Serial.print("Saved network SSID is ");
        Serial.println(ssid);

        Serial.print("Auto-connect in ");
        unsigned int end = millis() + TIMEOUT;
        
        int last_count = 0;
        while (countdown == true) {
            unsigned int remaining = end - millis();
            if ((remaining < 0) || (remaining > TIMEOUT)) {                
                break;
            } else {
                int count = (remaining / 1000);
                if (count != last_count) {
                    last_count = count;
                    Serial.print(count);
                    Serial.print("..");
                    if (Serial.available() > 1) {
                        countdown = false;
                    }
                }
            }
        }
        
        if (countdown == true) {
            Serial.println("Connecting...");
            connect(ssid.c_str(), password.c_str());
        } else {
            Serial.println("Connection aborted");
            wifiScan();
        }
    }
    
    esp_task_wdt_init(10, true); //enable panic so ESP32 restarts
    esp_task_wdt_add(NULL); //add current thread to WDT watch
}
void loop() {
    esp_task_wdt_reset();
    checkSerial();
    if ((WiFi.status() != WL_CONNECTED) && (connected == true)) {
      Serial.println("Lost connection to Wi-Fi. Reconnecting...");
      WiFi.disconnect();
      connected = false;      
      delay(100);
      connect(ssid.c_str(), password.c_str());          
    }
}

void wifiScan() {
    Serial.println("Searching for APs..");
    wifiCount = WiFi.scanNetworks();
    Serial.println("Networks found:");
    for (int i = 0; i < wifiCount; i++) {
        Serial.print("\t[");
        Serial.print(i);
        Serial.print("]\t(");
        Serial.print(WiFi.BSSIDstr(i));
        Serial.print(") ");
        Serial.print(WiFi.SSID(i));
        Serial.print(" [Signal ");
        Serial.print(WiFi.RSSI(i));
        Serial.println("dBm]");
        delay(10);        
    }
}



void checkSerial() {
  // command stuff
  for (int i = 0; i < Serial.available() && cmdStatus == 0; i++) { // if serial data is available to read
      cmdStatus = 0;
      cmdByte = Serial.read(); // read it
      if (cmdByte == 0x0A || cmdByte == 0x0D) { // newline and carriage return
          Serial.flush(); // clear the input buffer
          if (cmdBufferPosition == 0) { // if command is blank
            resetBuffers(); // reset buffers
          } else { // if the command is not blank
            cmdStatus = 1; // flag the command as 'ready for processing'
          }
      } else if (cmdByte == 0x7F) { // backspace
          if (cmdBufferPosition != 0) { // don't backspace further than the prompt
            cmdBufferPosition--;
            if (echoInput == 1) { // if echo is enabled, backspace on the client
             Serial.print('\b');
            }
          }
      } else { // other char, add to buffer
        // restrict to printable characters
        if (cmdByte >= 0x20  && cmdByte <= 0x7E) {
          cmdBuffer[cmdBufferPosition] = cmdByte; // append to buffer
          cmdBufferPosition++; // increment buffer position
        
          if (echoInput == 1) { // if echo is enabled, echo the character back to the client
             Serial.print(cmdByte);
          }
        }
      }
  }
  
  if (cmdStatus == 1) { // cmd received, but not processed
  
    // in case of backspace, truncate command buffer
    for (int i = cmdBufferPosition; i <= strlen(cmdBuffer); i++) {
      cmdBuffer[i] = NULL;
    }
    
    handleCommand(cmdBuffer); // process the command
    resetBuffers(); // clear the command buffers
  }
}

void connectIndex(int index, char *password) {
  ssid = WiFi.SSID(index);
  const char *ssid_chr = ssid.c_str();
  connect(ssid_chr, password);
}

void connect(const char *ssid, const char *password) {
  Serial.println("Connecting to network...");
  
  unsigned long start = millis();
  unsigned long duration = 0;
  WiFi.begin(ssid, password);
  
  while (WiFi.status() != WL_CONNECTED) {
      delay(500);
      Serial.print(".");
      duration = millis() - start;              
      if (duration > TIMEOUT) {
          Serial.println("WiFi: Connection failed. Is the password correct?");
          break;
      }
      
  }
  
  if (WiFi.status() == WL_CONNECTED) {
    Serial.println("WiFi: Connected to network");
    preferences.putString("ssid", ssid);
    preferences.putString("password", password);
    Serial.print("IP address is ");
    Serial.println(WiFi.localIP());
    connected = true;
  } else {
    connected = false;
  }
}

// serial command interpreter
void handleCommand(char* cmdBuffer) { // handles commands
  
  // init vars
  char *command = NULL;
  char *argument1 = NULL;
  char *argument2 = NULL;

  char *buf = cmdBuffer;
  
  command = strtok(buf, " "); // first word (command, before space)
  argument1 = strtok(NULL, " "); // second word (argument, after space)
  argument2 = strtok(NULL, " "); // third word (argument, after space)
  
  Serial.println(""); // newline
  
  // process command
  if (strcasecmp(command, "HELP") == 0) {
    Serial.println("Command help:");
    Serial.println("\tSCAN - Scan for networks");
    Serial.println("\tCONNECT <#> <password> - Connect to a listed network (passwords cannot have spaces)");    
    Serial.println("\tDISCONNECT - Disconnect from Wi-Fi"); 
    Serial.println("\tFORGET - Forget saved Wi-Fi"); 
    Serial.println("\tWSTATUS - Show current Wi-Fi status"); 
  } else if (strcasecmp(command, "SCAN") == 0) {
    wifiScan();
  } else if (strcasecmp(command, "CONNECT") == 0) {
      int index = atoi(argument1);
      if (index <= wifiCount) {          
          connectIndex(index, argument2);
      } else {
          Serial.print("Invalid network. Select a number between 0 and ");
          Serial.println(((int)wifiCount - 1));          
      }
  } else if (strcasecmp(command, "DISCONNECT") == 0) {
    if (connected == true) {
        Serial.println("Disconnecting..");
        connected = false;
        WiFi.disconnect();    
        Serial.println("Disconnected!");
    } else {
        Serial.println("Not connected!");
    }
  } else if (strcasecmp(command, "FORGET") == 0) {
    preferences.putString("ssid", "");
    preferences.putString("password", "");
    Serial.println("Saved network cleared");
  } else if (strcasecmp(command, "WSTATUS") == 0) {
    if (connected == false) {
      Serial.println("Not connected to network");      
    } else {
      Serial.print("Connected to ");
      Serial.println(ssid);
      
      Serial.print("RSSI: ");
      Serial.print(WiFi.RSSI());
      Serial.println("dBm");
      
      Serial.print("Our IP: ");
      Serial.println(WiFi.localIP());

      Serial.print("Our MAC: ");
      Serial.println(WiFi.macAddress());
    }
  } else {
      Serial.println("Unknown command. Enter HELP for help.");
  }
}

// reset the serial command buffers
void resetBuffers() { // resets command buffers and command state
  cmdStatus = 0; // reset the processing state
  cmdBufferPosition = 0; // reset the buffer position
  for (int x = 0; x < 32; x++) { // clear the buffer
    cmdBuffer[x] = NULL; // command buffer
    command[x] = NULL; // command
    argument1[x] = NULL; // command arguments
    argument2[x] = NULL; // command arguments
  }
  if (echoInput == 1) { // if echo is enabled, print a prompt
    Serial.println("");
    Serial.print(CMDPROMPT);
  }
}