1 // File: TelnetServer.ino for ESP8266 NodeMCU
   2 // 2015-12-07 Rudolf Reuter www.rudiswiki.de/wiki9 (search for "wifi")
   3 // 2015-12-17 RR, structure copied from example WiFiTelnetToSerial.ino
   4 //
   5 // Developed for debug purpose, use like the Arduino Serial Monitor.
   6 // Needs Arduino 1.6.5/6 to compile.
   7 //
   8 /*
   9  *   This library is free software; you can redistribute it and/or
  10   modify it under the terms of the GNU Lesser General Public
  11   License as published by the Free Software Foundation; either
  12   version 2.1 of the License, or (at your option) any later version.
  13 
  14   This library is distributed in the hope that it will be useful,
  15   but WITHOUT ANY WARRANTY; without even the implied warranty of
  16   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  17   Lesser General Public License for more details.
  18 
  19   You should have received a copy of the GNU Lesser General Public
  20   License along with this library; if not, write to the Free Software
  21   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  22  */
  23 
  24 #include <ESP8266WiFi.h>
  25 #include <Arduino.h>
  26 
  27 // Set these to your desired softAP credentials. They are not configurable at runtime.
  28 const char *ssid = "..........";
  29 const char *password = "..........";
  30 
  31 boolean debug = false;  // true = more messages
  32 //boolean debug = true;
  33 
  34 // LED is needed for failure signalling
  35 const short int BUILTIN_LED2 = 16;  //GPIO16 on NodeMCU (ESP-12)
  36 
  37 unsigned long startTime = millis();
  38 
  39 // provide text for the WiFi status
  40 const char *str_status[]= {
  41   "WL_IDLE_STATUS",
  42   "WL_NO_SSID_AVAIL",
  43   "WL_SCAN_COMPLETED",
  44   "WL_CONNECTED",
  45   "WL_CONNECT_FAILED",
  46   "WL_CONNECTION_LOST",
  47   "WL_DISCONNECTED"
  48 };
  49 
  50 // provide text for the WiFi mode
  51 const char *str_mode[]= { "WIFI_OFF", "WIFI_STA", "WIFI_AP", "WIFI_AP_STA" };
  52 
  53 //----------------------- WiFi handling
  54 void connectWifi() {
  55   Serial.print("Connecting as wifi client to SSID: ");
  56   Serial.println(ssid);
  57 
  58   // use in case of mode problem
  59   WiFi.disconnect();
  60   // switch to Station mode
  61   if (WiFi.getMode() != WIFI_STA) {
  62     WiFi.mode(WIFI_STA);
  63   }
  64 
  65   WiFi.begin ( ssid, password );
  66 
  67   if (debug ) WiFi.printDiag(Serial);
  68 
  69   // ... Give ESP 10 seconds to connect to station.
  70   unsigned long startTime = millis();
  71   while (WiFi.status() != WL_CONNECTED && millis() - startTime < 10000) {
  72     delay(500);
  73     Serial.print(".");
  74   }
  75   Serial.println("");
  76   // Check connection
  77   if (WiFi.status() == WL_CONNECTED) {
  78     Serial.print("WiFi connected; IP address: ");
  79     Serial.println(WiFi.localIP());
  80   } else {
  81     Serial.print("WiFi connect failed to ssid: ");
  82     Serial.println(ssid);
  83     Serial.print("WiFi password <");
  84     Serial.print(password);
  85     Serial.println(">");
  86     Serial.println("Check for wrong typing!");
  87   }
  88 }  // connectWiFi()
  89 
  90 void signalError() {  // loop endless with LED blinking in case of error
  91   while(1) {
  92       digitalWrite(BUILTIN_LED2, LOW);
  93       delay(300); // ms
  94       digitalWrite(BUILTIN_LED2, HIGH);
  95       delay(300); // ms
  96   }
  97 }
  98 
  99 
 100 // declare telnet server (do NOT put in setup())
 101 WiFiServer telnetServer(23);
 102 WiFiClient serverClient;
 103 
 104 void setup() {
 105   delay(1000);
 106   Serial.begin(115200);
 107   delay(1000);
 108   Serial.println("Sync,Sync,Sync,Sync,Sync");
 109   delay(500);
 110   Serial.println();
 111   // signal start
 112   pinMode(BUILTIN_LED2, OUTPUT);
 113   digitalWrite(BUILTIN_LED2, LOW);
 114   delay(100); // ms
 115   digitalWrite(BUILTIN_LED2, HIGH);
 116   delay(300); // ms
 117 
 118   Serial.print("Chip ID: 0x");
 119   Serial.println(ESP.getChipId(), HEX);
 120 
 121   Serial.println ( "Connect to Router requested" );
 122   connectWifi();
 123   if (WiFi.status() == WL_CONNECTED) {
 124     Serial.print("WiFi mode: ");
 125     Serial.println(str_mode[WiFi.getMode()]);
 126     Serial.print ( "Status: " );
 127     Serial.println (str_status[WiFi.status()]);
 128     // signal WiFi connect
 129     digitalWrite(BUILTIN_LED2, LOW);
 130     delay(300); // ms
 131     digitalWrite(BUILTIN_LED2, HIGH);      
 132   } else {
 133     Serial.println("");
 134     Serial.println("WiFi connect failed, push RESET button.");
 135     signalError();
 136   }
 137 
 138   telnetServer.begin();
 139   telnetServer.setNoDelay(true);
 140   Serial.println("Please connect Telnet Client, exit with ^] and 'quit'");
 141 
 142   Serial.print("Free Heap[B]: ");
 143   Serial.println(ESP.getFreeHeap());
 144 } // setup()
 145 
 146 
 147 void loop() {
 148   // look for Client connect trial
 149   if (telnetServer.hasClient()) {
 150     if (!serverClient || !serverClient.connected()) {
 151       if (serverClient) {
 152         serverClient.stop();
 153         Serial.println("Telnet Client Stop");
 154       }
 155       serverClient = telnetServer.available();
 156       Serial.println("New Telnet client");
 157       serverClient.flush();  // clear input buffer, else you get strange characters 
 158     }
 159   }
 160 
 161     while(serverClient.available()) {  // get data from Client
 162     Serial.write(serverClient.read());
 163   }
 164   
 165   if (millis() - startTime > 2000) { // run every 2000 ms
 166     startTime = millis();
 167 
 168     if (serverClient && serverClient.connected()) {  // send data to Client
 169       serverClient.print("Telnet Test, millis: ");
 170       serverClient.println(millis());
 171       serverClient.print("Free Heap RAM: ");
 172       serverClient.println(ESP.getFreeHeap());
 173     }
 174   }
 175   delay(10); // to avoid strange characters left in buffer
 176 }