10K ohms Resistor / 1k & 2k ohms resistor for voltage divider,.

If you are doing lots of things on both Arduino and ESP8266 NodeMCU. Apart from this we will also see how to use software serial library on Arduino and Serial1 on ESP8266 NodeMCU, So that you can transfer data with another serial port, which we will be helpful. Moreover, we will transfer DHT22 Sensor data from Arduino to NodeMCU and NodeMCU to Arduino. Serial communication is required when you want to transfer sensor data or any data from one device to another device, In our case it is ESP8266 NodeMCU and Arduino. In this tutorial we will learn how to make serial communication between Arduino to ESP8266 & ESP8266 to Arduino.