Arduino Uno + ESP8266 e1 - analogue sensor data display on simple internal web page

Projects Networking, Protocols, and Devices
1

Hi all,

General idea is to use my Arduino Uno project of gas sensor monitoring (simple one just MQ2 sensor display) and connect it to ESP to display data on web page on internal wifi network.

I have upload the following code to ESP and simple following code to Arduino. The ESP connects to the wifi. Displays the page with title, but no data. The pins are connected to 8 and 9 as stated in the codes. I am sure there is something wrong with serial communication, but can not figure it out.

I see on IDE serial monitor that Uno sending data, but they are not picked up by ESP.

Thank you so much for help!

---- ESP code ----

#include <ESP8266WiFi.h>
#include <SoftwareSerial.h>

SoftwareSerial espSerial(8, 9); // RX, TX

const char* ssid = "*****";
const char* password = "*****";

WiFiServer server(80);

void setup() {
  Serial.begin(9600);
  espSerial.begin(9600);

    delay(10);

  // Connect to WiFi network
  Serial.println();
  Serial.println();
  Serial.print("Connecting to ");
  Serial.println(ssid);
  WiFi.begin(ssid, password);
  while (WiFi.status() != WL_CONNECTED) {
    delay(1000);
    Serial.print(".");
  }
  Serial.println("");
  Serial.println("WiFi connected");

  // Start the server
  //server.on("/", handleRoot);
  server.begin();
  Serial.println("Server started");

}

void loop() {
  WiFiClient client = server.available();
  if (client) {
    Serial.println("New client");
    String currentLine = "";
    while (client.connected()) {
      if (client.available()) {
        char c = client.read();
        if (c == '\n') {
          if (currentLine.length() == 0) {
            client.println("HTTP/1.1 200 OK");
            client.println("Content-type:text/html");
            client.println("Connection: close");
            client.println();
            client.println("<!DOCTYPE HTML>");
            client.println("<html>");
            client.println("<head><title>Sensor Data</title></head>");
            client.println("<body>");
            client.println("<h1>Sensor Data</h1>");
            client.println("<p>");
            // Read sensor data from Arduino
            espSerial.println("read_sensor_data"); // Send command to Arduino
            String sensorData = "";
            while (espSerial.available()) {
              char c = espSerial.read();
              if (c != '\n') {
                sensorData += c;
              }
            }
            client.println(sensorData); // Print sensor data to web page
            client.println("</p>");
            client.println("</body>");
            client.println("</html>");
            break;
          } else {
            currentLine = "";
          }
        } else if (c != '\r') {
          currentLine += c;
        }
      }
    }
    client.stop();
    Serial.println("Client disconnected");
  }
}

---- arduino code ----


#include <SoftwareSerial.h>

SoftwareSerial mySerial(8, 9); // RX, TX

int sensorPin = A0;

void setup() {
  Serial.begin(9600); // Initialize hardware serial for debugging
  mySerial.begin(9600); // Initialize software serial for ESP8266
}

void loop() {
  int sensorValue = analogRead(sensorPin);
  Serial.print("sensor_data=");
  Serial.println(sensorValue);
  delay(1000);
}
2

You have

SoftwareSerial mySerial(8, 9); // RX, TX

presumably to communicate with the ESP but you never use mySerial in the sketch

Why not connect the sensor directly to the ESP ?

3

Hi Bob,

Thank you very much for fast answer... and gooooood catch.

Changed Arduino code to send data on mySerial...


void loop() {
  int sensorValue = analogRead(sensorPin);
  mySerial.print("sensor_data=");
  mySerial.println(sensorValue);
  delay(1000);
}

Still not working...

but I think something is wrong with getting data on ESP with this code:

            // Read sensor data from Arduino
            espSerial.println("read_sensor_data"); // Send command to Arduino
            String sensorData = "";
            while (espSerial.available()) {
              char c = espSerial.read();
              if (c != '\n') {
                sensorData += c;
              }
            }

Regarding connection of MQ directly to the ESP - I know this is possible. But eventually I would build the project with more sensors and display them on web + LCD on the arduino itself...

4

Fruther more:

Commented out the code:

///       espSerial.println("read_sensor_data"); // Send command to Arduino

TX pin on ESP connected to pin 8 directly. RX pin trough resisters to pin 9.

---still no result....

5

To troubleshoot place this line in your arduino code

Serial.println(sensorValue);

right after this line

mySerial.println(sensorValue);

and in ESP code place this line

Serial.println(sensorData);

right before this line

client.println(sensorData);

see what you get on your serial monitors

6

Hi mwrey,

Done... getting sensorValue fom Arduino, but not sensorData from ESP.

But this seems to be normal. Serial.println on Arduino would work on normal serial communication, but ESP is connected to Arduino trough pins 8 and 9, so Serial.println there would not sent anything to Arduino??? Or am I getting this wrong. SoftwareSerial is transferring this communication trough different pins, so that there is no noise between two sets of communication??? Do I understand this correct?

7

Hi all,

Solved the mystery! on ESP code I do not need to include SoftwareSerial library. ESP will communicate on normal serial communication not on changed ports.

new ESP code looks like this:


#include <ESP8266WiFi.h>

const char* ssid = "***";
const char* password = "****";

WiFiServer server(80);

void setup() {
  Serial.begin(9600);
    delay(10);

  // Connect to WiFi network
  WiFi.begin(ssid, password);
  while (WiFi.status() != WL_CONNECTED) {
    delay(1000);
  }
  server.begin();

}

void loop() {

            String sensorData = "";
            while (Serial.available()) {
              char c = Serial.read();
              if (c != '\n') {
                sensorData += c;
              }
            }


  WiFiClient client = server.available();
  if (client) {
    Serial.println("New client");
    String currentLine = "";
    while (client.connected()) {
      if (client.available()) {
        char c = client.read();
        if (c == '\n') {
          if (currentLine.length() == 0) {
            client.println("HTTP/1.1 200 OK");
            client.println("Content-type:text/html");
            client.println("Connection: close");
            client.println();
            client.println("<!DOCTYPE HTML>");
            client.println("<html>");
            client.println("<head><meta charset=""UTF-8""><title>Pregled senzorjev na unotu</title></head>");
            client.println("<body>");
            client.println("<h1>Pregled senzorjev na unotu</h1>");
            client.println("<p>");
            client.println(sensorData); // Print sensor data to web page
            client.println("</p>");
            client.println("</body>");
            client.println("</html>");
            break;
          } else {
            currentLine = "";
          }
        } else if (c != '\r') {
          currentLine += c;
        }
      }
    }
    client.stop();
delay(1000);

  }
}