Why doesn't serial communication work on Arduino Uno r3 and ESP8266 WiFi module?

Question

I have a simple problem here. I use an ESP8266 WiFi module and an Arduino Uno r3.

What I want is to receive a serial message from the ESP8266 on the Arduino Uno.

Note: I set the upload speed of the ESP8266 to 9600.

void setup() {
 Serial.begin(9600);
}
void loop() {
 Serial.write("hello friend");
 delay(2000);
}

Arduino Uno:

#include <SoftwareSerial.h>
SoftwareSerial mySerial(10, 11); //rx, tx
void setup() {
 Serial.begin(9600);
 mySerial.begin(9600);
}
String message = "";
boolean check = false;
void loop() {
 Serial.println(mySerial.available());
 mySerial.println("hindi nagagana");
 while (mySerial.available() > 0) {
 Serial.println(mySerial.readString());
 check = true;
 }
 if (check == true) {
 Serial.println(message);
 }
 delay(200);
}

Or any idea on how to control the Arduino Uno via the internet, such as a simple LED blink?

I used Firebase for databases an I plan to use ReactJs for webApp/Native App (nodeJs).

• Juraj: you print the empty String message forever once something is received on mySerial
• Rudy Albachten: Are you sure you have tx connected to rx and vice versa? You could use the serial monitor to test each half in isolation.

Answer 1

i think you should change Serial.write() to Serial.print() because Serial.write() is for send data as bytes or series of bytes and Serial.print() send as human-readable text.
Reference:
Serial.write()
https://www.arduino.cc/reference/en/language/functions/communication/serial/write/
Serial.print()
https://www.arduino.cc/reference/en/language/functions/communication/serial/print/
esp 8266 code:

void setup()
{
 Serial.begin(9600);
}
void loop(){
 Serial.print("hello friend");
 delay(2000);
 
 }

• Art Lisboa: Hi thank you for answering my question it really help but the thing is , its not working T_T is there any library or board installation do i need to install?? Im ran out of google stuff on the internet
• Juraj: write and print are same for string
• Metronomy31: Can you add your wiring diagram into question?