Board Review ESP8266 with OLED

This WeMos labeled board has a OLED display using the SSD1306 chip on a ESP-12E module based ESP8266 board.

Overview table

GPIO	Pin	Functionality	Remarks
	AD	Analog input
GPIO16	D0	connector
GPIO5	D1	connector	I2C-SDA for display
GPIO4	D2	connector	I2C-SCL for display
GPIO0	D3	Button FLASH
GPIO2	D4	connector, LED	LED on ESP-12
GPIO14	D5	connector
GPIO12	D6	connector
GPIO13	D7	connector
GPIO15	D8	connector
GPIO3	D9	connector
GPIO1	D10	connector
	—	I2C address for display	60 (=0x3c)
	—	Display size	128 * 64
Reset		Button RST

Features

It is a board that combines the nodeMCU setup with a OLED.

The display is using the OLED technology and the SSD1306 chip is attached using the I2C bus. A library for driving this chip is available “ESP8266 and ESP32 Oled Driver for SSD1306 display”. It supports the 128x64 pixel of the display.

The blue LED on the ESP-12 can be used GPIO2(D4).

The FLASH and RESET buttons are available like on the nodeMCU boards.

Critics

Onboard LED

No real Low Power

The OLED display is good quality, but it is taking some power even when not used. That makes this combination almost useless for pure battery appliances when a long lifetime is required.

I2C / WIRE Bus

The internally used I2C Bus for the connection with the OLED is also available on the connectors. Therefore it is possible to add more I2C bus devices on the same bus.

Also the board doesn’t use the common and default pins that are defined by SCL=GPIO5(D1) and SDA=GPIO4(D2).

The board uses

SCL = GPIO4 (D2) (yellow) and
SDA = GPIO5 (D1) (blue)

Board configuration

The display configuration is the only specific entry in env.json:

{
  "device": {
    "0": {
      "name": "wemosding",
      "reboottime": "24h",
      "description": "IoT Ding with display",
      "logfile": 1,
      "led": "D4",
      "button": "D3",
      "I2C-SDA": "D1",
      "I2C-SCL": "D2"
    }
  },
  "ota": {
    "0": {
      "passwd": "123"
    }
  },
  "ssdp": {
    "0": {
      "ModelUrl": "https://www.mathertel.de/Arduino",
      "Manufacturer": "Matthias Hertel",
      "ManufacturerURL": "https://www.mathertel.de"
    }
  },
  "displaySSD1306": {
    "0": {
      "description": "local display",
      "address": "0x3C",
      "loglevel": 2,
      "height": 64
    }
  }
}