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NodeMCU/ ESP28266

NodeMCU is a firmware that allows you to program the ESP8266 chip with a LUA script, or C/C++ via the Arduino IDE.

The NodeMCU programming model is similar to that of Node.js, only in Lua. It is asynchronous and event-driven. Many functions, therefore, have parameters for callback functions.

While the ESP8266 is often used as a ‘dumb’ Serial-to-WiFi bridge, it’s a very powerful microcontroller on its own, as it's basically an Arduino.

Power

The chip itself uses 3.3v, but if the board has a usb port, then it knows that usb comes with a 5v supply, so it probably has a regulator built-in to convert the 5v to the 3.3v the chip needs.

A phone charger or power bank should work just fine.

https://tttapa.github.io/ESP8266/Chap04%20-%20Microcontroller.html

Setup

  1. Start Arduino IDE and open Preferences window.

  2. Enter http://arduino.esp8266.com/stable/package_esp8266com_index.json into Additional Board Manager URLs field. You can add multiple URLs, separating them with commas.

  3. Open Boards Manager from Tools > Board menu and install esp8266 platform (and don't forget to select your ESP8266 board from Tools > Board menu after installation).

GPIO

NodeMCU Development kit provides access to the GPIOs of ESP8266. The NodeMCU Dev kit pins are numbered differently than internal GPIO notations of ESP8266. For example, the D0 pin on the NodeMCU Dev kit is mapped to the internal GPIO pin 16 of ESP8266.

// Pins can be assigned like this
int PIN_A = D7 // GPIO13
int PIN_A = 13 // D7

// This can also be used. Takes less RAM.
#define PIN_A 13

LED example

int LED = D7;

void setup() {
  pinMode(LED, OUTPUT);
}

void loop() {
  digitalWrite(LED, LOW);
  delay(1000);
  digitalWrite(LED, HIGH);
  delay(2000);
}

Remote LED light

Upload the code into NodeMCU, and go to the local address specified in the serial monitor in order to toggle the LED light, connected in a classic GPIO way.

#include <ESP8266WiFi.h>

const char* ssid = "WIFI_NAME";
const char* password = "WIFI_PASSWORD";

int ledPin = 13; // GPIO13---D7 of NodeMCU
WiFiServer server(80);

void setup() {
  Serial.begin(115200);
  delay(10);

  pinMode(ledPin, OUTPUT);
  digitalWrite(ledPin, LOW);

  // Connect to WiFi network
  Serial.println();
  Serial.println();
  Serial.print("Connecting to ");
  Serial.println(ssid);

  WiFi.begin(ssid, password);

  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }
  Serial.println("");
  Serial.println("WiFi connected");

  // Start the server
  server.begin();
  Serial.println("Server started");

  // Print the IP address
  Serial.print("Use this URL to connect: ");
  Serial.print("http://");
  Serial.print(WiFi.localIP());
  Serial.println("/");

}

void loop() {
  // Check if a client has connected
  WiFiClient client = server.available();
  if (!client) {
    return;
  }

  // Wait until the client sends some data
  Serial.println("new client");
  while(!client.available()){
    delay(1);
  }

  // Read the first line of the request
  String request = client.readStringUntil('\r');
  Serial.println(request);
  client.flush();

  // Match the request

  int value = LOW;
  if (request.indexOf("/LED=ON") != -1)  {
    digitalWrite(ledPin, HIGH);
    value = HIGH;
  }
  if (request.indexOf("/LED=OFF") != -1)  {
    digitalWrite(ledPin, LOW);
    value = LOW;
  }

// Set ledPin according to the request
//digitalWrite(ledPin, value);

  // Return the response
  client.println("HTTP/1.1 200 OK");
  client.println("Content-Type: text/html");
  client.println(""); //  do not forget this one
  client.println("<!DOCTYPE HTML>");
  client.println("<html>");

  client.print("Led is now: ");

  if(value == HIGH) {
    client.print("On");
  } else {
    client.print("Off");
  }
  client.println("<br><br>");
  client.println("<a href=\"/LED=ON\"\"><button>On </button></a>");
  client.println("<a href=\"/LED=OFF\"\"><button>Off </button></a><br />");
  client.println("</html>");

  delay(1);
  Serial.println("Client disonnected");
  Serial.println("");
}