how to do Arduino to esp8266 communication

Question

I am trying to do Arduino to ESP8266 communication, but I am not able to send data to esp8266. However I can receive data from esp8266.

Here if my Arduino code:

#include <SoftwareSerial.h>
SoftwareSerial ESPserial(0, 1); // RX | TX
void setup()
{
 Serial.begin(115200); // communication with the host computer
 // Start the software serial for communication with the ESP8266
 ESPserial.begin(9600);
 Serial.println("Enter 1 to turn led high & 2 to turn led low.");
}
// the loop function runs over and over again forever
void loop() {
 // listen for communication from the ESP8266 and then write it to the serial monitor
 if ( ESPserial.available() ) {
 Serial.write( ESPserial.read() );
 }
 // listen for user input and send it to the ESP8266
 if ( Serial.available() ) {
 ESPserial.write( Serial.read() );
 }
}

Here is esp8266 code:

void setup()
{
 Serial.begin(9600); // communication with the host computer
 // Start the software serial for communication with the ESP8266
 // initialize digital pin LED_BUILTIN as an output.
 pinMode(LED_BUILTIN, OUTPUT);
}
// the loop function runs over and over again forever
void loop() {
 Serial.println("ESP -- Hello");
 delay(1000);
 // listen for user input and send it to the ESP8266
 if ( Serial.available() ) {
 int ledState = Serial.parseInt();
 if (ledState == 1) {
 digitalWrite(LED_BUILTIN, HIGH); // turn the LED on (HIGH is the voltage level)
 Serial.println("ESP Led On\n");
 }
 if (ledState == 2) {
 digitalWrite(LED_BUILTIN, LOW); // turn the LED off by making the voltage LOW
 Serial.println("ESP Led Off\n");
 }
 }
}

Once I upload both sketches, then I can see it terminal " ESP -- Hello " keep printing comming from esp8266 but when I enter 1 or 2, its not sent to esp8266 due to which I never see "ESP led on/off" messages , so correct me guys what mistake I am making.

• Majenko: Don't ever use SoftwareSerial in pins 0 and 1! And never use pins 0 and 1 for anything if you are using Serial for Arduino to PC communication.
• user889030: @Majenko ok thanks then how can i solve the issue of this communication on UNO i have just these one RX and TX pair it 0,1 pins so should i try the same code on mega2560
• Juraj: you can use SoftwareSerial on any pair of pins. that is why it is called 'software' Serial

Answer 1

using SoftSerial on the hardware serial isn't working on Arduino properly as sometime data receive and sometime not with garbage added so Using digital pins other 2, & 3 other than hardware serial resolved the issue.

• MatsK: Perhaps you should clarify that using SoftSerial on the hardware serial isn't working, choose any other digital pins than the hardware serial pins.