D1 Mini

• RST: Reset Pin - Pull this pin LOW to reset the microcontroller.
• A0 (ADC0): Analog Input Pin - Can only handle 3.3V maximum. Reads analog signals (0-3.3V), which are converted to a 10-bit digital value (0-1023).
• D0 (GPIO16): Digital Pin - No PWM. Can be used for digital input/output (HIGH/LOW).
• D1 (GPIO5): Digital Pin - Supports I2C SCL (clock). Can also function as a PWM pin.
• D2 (GPIO4): Digital Pin - Supports I2C SDA (data). Can also function as a PWM pin.
• D3 (GPIO0): Digital Pin - Pulled up internally. Can function as a PWM pin. Important Note: Connected to the boot mode process, avoid using for critical functions unless you understand its boot mode implications.
• D4 (GPIO2): Digital Pin - Pulled up internally. Also connected to the built-in LED on the D1 Mini. Can function as a PWM pin. Similar to D3, it's linked to the boot process.
• D5 (GPIO14): Digital Pin - SPI SCK (Serial Clock) pin when using the SPI protocol. Can function as a PWM pin.
• D6 (GPIO12): Digital Pin - SPI MISO (Master In, Slave Out) pin when using the SPI protocol. Can function as a PWM pin.
• D7 (GPIO13): Digital Pin - SPI MOSI (Master Out, Slave In) pin when using the SPI protocol. Can function as a PWM pin.
• D8 (GPIO15): Digital Pin - SPI SS (Slave Select) pin when using the SPI protocol. Pulled down internally. Can function as a PWM pin.
• TX (GPIO1): Transmit Pin - Used for serial communication. Can also be used for general-purpose I/O but avoid if using Serial.
• RX (GPIO3): Receive Pin - Used for serial communication. Can also be used for general-purpose I/O but avoid if using Serial.
• 3V3 - Provides 3.3V output. Powers external components if needed.
• 5V - Provides 5V output. Can power the board when connected to a 5V power source.
• G (Ground) - Common ground pin.

• Boot Mode Pins: Be careful when using GPIO0, GPIO2, and GPIO15 (D3, D4, and D8), as they have special boot-related functions. Pulling these pins to the wrong state during boot can prevent the board from starting correctly.
  • D3, should be HIGH during boot.
  • D4, should be HIGH during boot.
  • D8, should be LOW during boot.

• I2C (D1 and D2):
  
  • D1 (GPIO5) acts as SCL (clock) and D2 (GPIO4) acts as SDA (data) for I2C communication.

• SPI (D5, D6, D7, D8):
  
  • The D1 Mini uses the following GPIO pins for SPI communication:
    • D5 (SCK)
    • D6 (MISO)
    • D7 (MOSI)
    • D8 (SS)

• PWM Pins:
  
  • Almost all the digital pins (D0–D8) can be used for PWM (Pulse Width Modulation), which is helpful for controlling brightness of LEDs or speed of motors.

Overview of the D1 Mini​

The D1 Mini is a compact and affordable development board based on the ESP8266 microcontroller, widely known for its built-in Wi-Fi capabilities, which make it ideal for IoT (Internet of Things) projects. The D1 Mini is popular due to its small form factor, ease of use, and compatibility with the Arduino IDE, making it a top choice for hobbyists, makers, and developers.

Key Features:​

• ESP8266 microcontroller at the core, operating at 80/160 MHz clock speed.
• Built-in Wi-Fi for wireless communication, making it a powerful tool for IoT applications.
• 4 MB of Flash memory, providing storage for code and other data.
• 11 digital I/O pins: Configurable for various purposes, including GPIO, PWM, I2C, and SPI.
• 1 analog input (A0), used to read voltage levels up to 3.3V.
• Multiple power options: Can be powered via USB or through its 5V or 3.3V pins.

Common Uses:​

• IoT Projects: The D1 Mini’s Wi-Fi capability makes it ideal for IoT applications such as home automation, sensor networks, smart appliances, etc.
• Web Servers: Its onboard Wi-Fi can serve small web pages to monitor or control devices remotely.
• Sensor Integration: With its GPIO pins and I2C bus, the D1 Mini easily interfaces with sensors to create a wireless sensor network.
• Prototyping: Given its small size and versatility, it’s used to rapidly prototype Wi-Fi-based electronics projects.

Development Environment:​

The D1 Mini is compatible with the Arduino IDE, which means users can easily program it with the familiar Arduino language and ecosystem. Additionally, it can be programmed using MicroPython or the Lua scripting language, offering flexibility for various user preferences.