https://arduino.stackexchange.com/questions/78552/wiring-up-an-esp-01-to-nano?answertab=votes#tab-top

https://www.electronicslovers.com/2017/11/learn-how-to-setup-wifi-module-esp8266.html

https://www.youtube.com/watch?v=YKn2ZXYb_EI

arduino nano esp8266 esp 01 wifi

use buck converter (LM2596) for 3.3v nanoesp01cablage.jpg

#include <SoftwareSerial.h>
SoftwareSerial softSerial(2, 3); // RX, TX
 
void setup() 
{
  uint32_t baud = 9600;
  Serial.begin(baud);
  softSerial.begin(baud);
  Serial.print("SETUP!! @");
  Serial.println(baud);
}
 
void loop() 
{
    while(softSerial.available() > 0) 
    {
      char a = softSerial.read();
      if(a =='\0')
        continue;
      if(a != 'r' && a != 'n' && (a < 32))
        continue;
      Serial.print(a);
    }
    
    while(Serial.available() > 0)
    {
      char a = Serial.read();
      Serial.write(a);
      softSerial.write(a);
    }
}