What is LOLIN (formerly WEMOS)?

LOLIN boards are compact, affordable development boards built around Espressif’s Wi-Fi-enabled chips. Popular picks include the LOLIN D1 mini, LOLIN D1 R2, and LOLIN32 (ESP32-based). They’re perfect for IoT projects, home automation, web-controlled gadgets, and quick sensor prototypes.

• Built-in Wi-Fi: No extra shield needed.
• Arduino-compatible: Use the familiar Arduino IDE.
• Tiny footprint: Great for breadboards and enclosures.
• Stackable shields: Displays, relays, motor drivers & more.

Step-by-Step: Arduino IDE Setup

1. Open File → Preferences and paste this into Additional Boards Manager URLs:

   https://arduino.esp8266.com/stable/package_esp8266com_index.json

2. Go to Tools → Board → Boards Manager…, search for ESP8266, and click Install.
3. Select your board: Tools → Board → LOLIN (WEMOS) D1 R2 & mini.
4. Connect the board via USB. If it doesn’t show up, install the CH340 (or CP2102) USB driver for your OS.
5. Select the correct Port under Tools → Port.

Pro tip: If uploads fail, try another USB cable (must be data-capable), switch ports, or lower upload speed under Tools.

Your First Sketch: Blink (Built-in LED)

Paste this into a new sketch and upload. On many D1 minis the built-in LED is on pin LED_BUILTIN (mapped internally):

// LOLIN D1 mini Blink
void setup() {
  pinMode(LED_BUILTIN, OUTPUT); // Built-in LED pin
}
void loop() {
  digitalWrite(LED_BUILTIN, LOW);  // LED ON (active low on ESP8266)
  delay(500);
  digitalWrite(LED_BUILTIN, HIGH); // LED OFF
  delay(500);
}

On ESP8266, the LED is usually active-low (LOW = on). That’s not a bug—just a quirk of the board design.

Wi-Fi Quickstart: Test Connection

Confirm the Wi-Fi radio is happy by connecting to your network and printing the IP address:

#include <ESP8266WiFi.h>

const char* ssid     = "YourSSID";
const char* password = "YourPassword";

void setup() {
  Serial.begin(115200);
  WiFi.begin(ssid, password);
  Serial.print("Connecting");
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }
  Serial.println();
  Serial.print("Connected! IP: ");
  Serial.println(WiFi.localIP());
}

void loop() {
  // Your IoT magic goes here
}

LOLIN D1 mini Pinout (ESP8266)

Handy mapping when translating between “Dx” silk labels and actual GPIO numbers:

Voltage gotcha: A0 reads up to ~1.0V. Use a divider for sensors that output higher voltages.

What Can You Build?

• Wi-Fi temperature & humidity sensors (MQTT or web dashboard)
• Smart lights and LED effects (WS2812/Neopixel)
• Home automation triggers (relays, contact sensors)
• Remote data loggers (to cloud or local server)

Troubleshooting: Windows Not Recognizing the Board

• Install driver: Most D1 minis use the CH340 USB-serial driver (some use CP2102).
• Try a different cable: Many “charge-only” cables lack data lines.
• Check Device Manager: Look under Ports (COM & LPT) for a new COM port.
• Re-select the port in Arduino IDE: Tools → Port.
• Boot mode pins: Avoid pulling GPIO0, GPIO2, or GPIO15 to the wrong levels at boot.

Next Steps

1. Add a sensor shield and read temperature via I2C on D1/D2.
2. Serve a tiny web page from the board to view sensor data.
3. Publish readings to MQTT and build a dashboard.

Focus keyphrase: LOLIN D1 mini tutorial