Connecting an ESP8266 NodeMCU to an Arduino Uno Using UART Communication

When working on your projects, you might find yourself in a situation where

you need to utilize both an Arduino Uno and an ESP8266 NodeMCU. This is often

due to the fact that the NodeMCU has an on-chip microcontroller and can be programmed

using the Arduino IDE. However, sometimes your project might require more analog pins or

GPIOs than what is available on the NodeMCU. In such cases, you can effectively use these

two devices in tandem through UART communication (also known as serial communication).

Understanding UART Communication Between Arduino and NodeMCU

The UART mode of communication allows the Arduino and NodeMCU to communicate with each

other using Tx (transmit) and Rx (receive) pins. This communication can be managed

using the SoftwareSerial Library in the Arduino IDE, which helps in simulating digital

serial communication using two GPIO pins on each microcontroller.

Setting Up UART Communication on NodeMCU

To establish UART communication, you first need to configure the NodeMCU. Here's

an example of how you can set up the communication:

Step 1: Include and Initialize the SoftwareSerial Library

include SoftwareSerial.h // Defining the software serial librarySoftwareSerial mySerial(D7, D6); // Creating the object of the library as mySerial and defining the D7 pin as Rx pin and D6 pin as Tx pinvoid setup {  (115200); // Starting the software serial at 115200 baud rate  // Your setup code}

Step 2: Send Data from NodeMCU to Arduino

void loop {  String payload  "DATA1 DATA2"; // Example data  (payload); // Print the data to the software serial monitor  // Your remaining code}

Setting Up UART Communication on Arduino

Similarly, you need to set up the Arduino Uno to read the data from the NodeMCU. Here's

an example of how you can achieve this:

Step 1: Include and Initialize the SoftwareSerial Library

include SoftwareSerial.h // Defining the software serial librarySoftwareSerial mySerial(6, 7); // Creating the object of the library as mySerial and defining the 6 pin as Rx pin and 7 pin as Tx pinvoid setup {  (115200); // Starting the software serial at 115200 baud rate  pinMode(10, OUTPUT); // Defining pin 10 as an output pin  // Your setup code}

Step 2: Read and Process Data from NodeMCU

void loop {  if (mySerial.available()  0) { // Checks if anything is present on the software serial monitor    String payload  (); // Read that data and store it in payload variable    // Now, suppose you want to trigger an LED connected at pin 10    if (payload  "DATA1") { // Compare both strings      digitalWrite(10, HIGH);    } else if (payload  "DATA2") { // Compare both strings      digitalWrite(10, LOW);    }  }}

Conclusion

This brief guide has demonstrated how to effectively communicate between an Arduino

Uno and an ESP8266 NodeMCU using UART (Serial) communication. By setting up the

SoftSerial library, you can easily share data and control GPIO pins across these two

devices. Such a setup is particularly useful for projects that require extensive

communication and the flexibility of using both microcontrollers.

Related Keywords

ESP8266 NodeMCU Arduino Uno UART Communication SoftwareSerial Library