NodeMCU ESP8266 12-E

Arduino-like IoT development using an ESP8266.

Contents


While not strictly an arduino, these development boards operate and are used very similarly.

Brief overview of the NodeMCU ESP8266

Let's unpack that name before anything else:

  1. NodeMCU - an open-source firmware written in Lua for the ESP8266.
  2. ESP8266 - a low-cost wifi microchip produced by Espressif Systems, these can be purchased stand-alone or as part of a development board.

The term NodeMCU ESP8266 is often used to refer to the development boards and while these development boards are not technically arduino's, but they are arduino-like and are supported by the arduino IDE.

Amica NodeMCU ESP8266

Pins

Looking at the top of the board with the USB port pointing down:

Description Pin Label BOARD Pin Label Description
ADC0
TOUT		 A0 D0 GPIO16
User, Wake
(r/w only, no interrupt)
Reserved RSV D1 GPIO5
Reserved RSV D2 GPIO4
GPIO10
SDD3		 SD3 D3 GPIO0
FLASH
GPIO09
SDD2		 SD2 D4 GPIO02
TXD1
MOSI
SDD1		 SD1 3V3 3.3 Volt
CS
SDCMD		 CMD GND Ground
MISO
SDD0		 SD0 D5 GPIO14
HSCLK
SCLK
SDCLK		 CLK D6 GPIO12
HMISO
Ground GND D7 GPIO13
RXD2
HMOSI
3.3 Volt 3V3 D8 GPIO15
TXD2
HCS
EN EN D9 GPIO3
RXDO
RST RST D10 GPI01
TXD0
Ground GND GND Ground
VIN 5 Volt VIN 3V3 3.3 Volt
Available GPIO Pins

The NodeMCU ESP8266 12-E has thirteen (13) General Purpose Input/Output (GPIO) pins exposed on the board, however not all of these pins are suggested for use.

Refer to https://randomnerdtutorials.com/esp8266-pinout-reference-gpios/ for a great write-up on the pins.

Safely usable GPIO Pins

Some of the GPIO pins have multiple uses or can have unexpected behaviour at boot, the following pins are generally considered safe for both Input and Output:

  • D1 (GPIO5)
  • D2 (GPIO4)
  • D5 (GPIO14)
  • D6 (GPIO12)
  • D7 (GPIO13)
Analog Pins

The NodeMCU has one (1) Analog pin available (A0/ADC0).

Sensors

Arduino sensors can be used.

If the sensor requires 5v of power you can use the VIN pin to power it but you will need to use a voltage divider if the sensor returns more than 3.3v to prevent frying your board.

Development Tools

Arduino IDE

Good step-by-step guide to installing the Arduino IDE and the ESP8266 modules: https://microcontrollerslab.com/how-to-install-esp8266-board-arduino-ide/

If you're looking for custom logic or just want to write the code yourself the arduino IDE is solid and works well with the ESP8266.

Tasmotizer

I'm a big fan of Tasmotizer for quickly configuring the ESP8266 boards for use with MQTT.

Since I'm mostly building simple sensors to integrate with Home Assistant using MQTT, Tasmotizer saves me a lot of time.