Arduino and ESP8266 - how to send/receive data between serial and TCP port

BitSeeker · May 28, 2019, 7:28pm

I would ideally like the user of the project to be able to buy and ESP8266, connect it to the Arduino and have the sketch on the Arduino configure the ESP ready for use. The user sets the AP details in the sketch.

Ok, so I have got as far connecting the ESP8266 to a WiFi AP and given it an IP address. I now want to be able to send data from the Arduino serial to a TCP port and to receive data from the TCP port and pass it to the serial port on the Arduino. The idea is to be able to telnet into the TCP port and communicate with the Arduino. How do I go about this?

I have seen and am confused by much of the information online which seems to require a sketch to be uploaded to the ESP. But doesn't that overwrite the original firmware? A number of sketches have the ESP connecting to a server on another computer. Here I need to do the opposite - to be able to telnet from a PC and communicate with the Arduino over the ESP serial link. I expected this to be easy, but am now wondering whether this is even possible?

Finally, how does one set up a web portal on the ESP8266 so that the user can change the configuration of the device?

If anyone can point me at suitable clear tutorials on the subject, and by all means tell me if what I am trying to do is impossible, this would be appreciated.

buckstucky · May 28, 2019, 11:37pm

github.com/esp8266/Arduino

WiFi Telnet Server for Serial Monitor use - provided

opened 10:42AM - 07 Dec 15 UTC

closed 05:16PM - 19 Oct 17 UTC

rudi48

Hello, I needed for the **stand alone operation** application debugging informat…ion. For that purpose I thought, that a **Telnet connection** would be the right choice. I found an example program **WiFiTelnetToSerial.ino**, which can serve multiple clients. For my purpose, that is too complex, so I tried to make it simple. The result is shown in the source listing on this page. Every 2 seconds, the **time millis()** and **freeHEAP()** ist send to the attached Telnet Client. The program was tested with success with the following **Telnet Clients**: - telnet (Linux NetKit 0.17) Linux Ubuntu 14.04 32Bit - PuTTY version 0.63, Windows 7 64Bit - telnet Mac OS X 10.11.1 ``` C // File: TelnetServer.ino for ESP8266 NodeMCU // 2015-12-07 Rudolf Reuter www.rudiswiki.de/wiki9 (search for "wifi") // 2015-12-17 RR, structure copied from example WiFiTelnetToSerial.ino // // Developed for debug purpose, use like the Arduino Serial Monitor. // Needs Arduino 1.6.5/6 to compile. // /* * This library is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 2.1 of the License, or (at your option) any later version. This library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details. You should have received a copy of the GNU Lesser General Public License along with this library; if not, write to the Free Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA */ #include <ESP8266WiFi.h> #include <Arduino.h> // Set these to your desired softAP credentials. They are not configurable at runtime. const char *ssid = "............."; const char *password = ".............."; boolean debug = false; // true = more messages //boolean debug = true; // LED is needed for failure signalling const short int BUILTIN_LED2 = 16; //GPIO16 on NodeMCU (ESP-12) unsigned long startTime = millis(); // provide text for the WiFi status const char *str_status[]= { "WL_IDLE_STATUS", "WL_NO_SSID_AVAIL", "WL_SCAN_COMPLETED", "WL_CONNECTED", "WL_CONNECT_FAILED", "WL_CONNECTION_LOST", "WL_DISCONNECTED" }; // provide text for the WiFi mode const char *str_mode[]= { "WIFI_OFF", "WIFI_STA", "WIFI_AP", "WIFI_AP_STA" }; //----------------------- WiFi handling void connectWifi() { Serial.print("Connecting as wifi client to SSID: "); Serial.println(ssid); // use in case of mode problem WiFi.disconnect(); // switch to Station mode if (WiFi.getMode() != WIFI_STA) { WiFi.mode(WIFI_STA); } WiFi.begin ( ssid, password ); if (debug ) WiFi.printDiag(Serial); // ... Give ESP 10 seconds to connect to station. unsigned long startTime = millis(); while (WiFi.status() != WL_CONNECTED && millis() - startTime < 10000) { delay(500); Serial.print("."); } Serial.println(""); // Check connection if (WiFi.status() == WL_CONNECTED) { Serial.print("WiFi connected; IP address: "); Serial.println(WiFi.localIP()); } else { Serial.print("WiFi connect failed to ssid: "); Serial.println(ssid); Serial.print("WiFi password <"); Serial.print(password); Serial.println(">"); Serial.println("Check for wrong typing!"); } } // connectWiFi() void signalError() { // loop endless with LED blinking in case of error while(1) { digitalWrite(BUILTIN_LED2, LOW); delay(300); // ms digitalWrite(BUILTIN_LED2, HIGH); delay(300); // ms } } // declare telnet server (do NOT put in setup()) WiFiServer telnetServer(23); WiFiClient serverClient; void setup() { delay(1000); Serial.begin(115200); delay(1000); Serial.println("Sync,Sync,Sync,Sync,Sync"); delay(500); Serial.println(); // signal start pinMode(BUILTIN_LED2, OUTPUT); digitalWrite(BUILTIN_LED2, LOW); delay(100); // ms digitalWrite(BUILTIN_LED2, HIGH); delay(300); // ms Serial.print("Chip ID: 0x"); Serial.println(ESP.getChipId(), HEX); Serial.println ( "Connect to Router requested" ); connectWifi(); if (WiFi.status() == WL_CONNECTED) { Serial.print("WiFi mode: "); Serial.println(str_mode[WiFi.getMode()]); Serial.print ( "Status: " ); Serial.println (str_status[WiFi.status()]); // signal WiFi connect digitalWrite(BUILTIN_LED2, LOW); delay(300); // ms digitalWrite(BUILTIN_LED2, HIGH); } else { Serial.println(""); Serial.println("WiFi connect failed, push RESET button."); signalError(); } telnetServer.begin(); telnetServer.setNoDelay(true); Serial.println("Please connect Telnet Client, exit with ^] and 'quit'"); Serial.print("Free Heap[B]: "); Serial.println(ESP.getFreeHeap()); } // setup() void loop() { // look for Client connect trial if (telnetServer.hasClient()) { if (!serverClient || !serverClient.connected()) { if (serverClient) { serverClient.stop(); Serial.println("Telnet Client Stop"); } serverClient = telnetServer.available(); Serial.println("New Telnet client"); serverClient.flush(); // clear input buffer, else you get strange characters } } while(serverClient.available()) { // get data from Client Serial.write(serverClient.read()); } if (millis() - startTime > 2000) { // run every 2000 ms startTime = millis(); if (serverClient && serverClient.connected()) { // send data to Client serverClient.print("Telnet Test, millis: "); serverClient.println(millis()); serverClient.print("Free Heap RAM: "); serverClient.println(ESP.getFreeHeap()); } } delay(10); // to avoid strange characters left in buffer } ``` Regards, Rudolf ## <bountysource-plugin> Want to back this issue? **[Post a bounty on it!](https://www.bountysource.com/issues/28912592-wifi-telnet-server-for-serial-monitor-use-provided?utm_campaign=plugin&utm_content=tracker%2F14245935&utm_medium=issues&utm_source=github)** We accept bounties via [Bountysource](https://www.bountysource.com/?utm_campaign=plugin&utm_content=tracker%2F14245935&utm_medium=issues&utm_source=github). </bountysource-plugin>

BitSeeker · May 29, 2019, 8:49am

Thanks. I think I have realised that the best way forward is to program the ESP8266 directly and I have now figured out how to add the ESP8266 board to the Arduino IDE.

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Arduino and ESP8266 - how to send/receive data between serial and TCP port

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