WeMos ESP8266 board with OLED and 18650

This board from WeMos has a OLED display on a ESP-12E module based ESP8266 board with a joystick input, LiIon Battery support and on/off switch.

/boards/esp8266/wemos18650.jpg

This board is equipped with:

ESP8266-12 module
OLED display based on the SSD1306 chip
A „joystick“ type of button that can be used as input and hardware reset.
A standard 18650 li-ion battery holder attached to the back
Charging chip for charging through the USB port
A power switch that separates all power consumption from the battery

Arduino Board Configuration

The Arduino Board Manager supports this board by installing the esp8266 by ESP8266 Community package. It can be used with the following settings:

Board: NodeMCU (ESP-12E Module)
CPU Frequency: 80 MHz
VTables: Flash
C++ Exception: Disabled
Stack Protection: Disabled
SSL Support: AllSSL Ciphers (most compatible)
MMU: 32kB cache + 32kB
IRAM (balanced)* Upload Speed: 921600
Non-32-Bit Access: Use pgm_read macros for IRAM/PROGMEM
Flash Size: 4MByte (FS:2MB OTA:~1019kB)
Builtin Led: 2+
IwIP Variant: v2 Lower Memory
Debug port: Serial
Debug level: None
Erase Flash: All Flash Contents on first upload, then Only Sketch
Upload Speed: 921600

This setting is identical to the standard NodeMCU settongs. However the features on the board are extended and not all signals are available to connectors.

OLED Display

The display is using the OLED technology and the chip is attached using the internal I2C bus and is supported by the SSD1306 Element and Display adapter.

The display resolution is 128x64 pixels.

The display can be used by configuring the DisplaySSD1306 Element.

The full configuration is provided below.

Joystick

The joystick button is connected to 4 input pins and to the reset pin as well this makes this button almost useless for games and menu selection functionality because it will happen by accident that the reset direction (move to the right) is activated.

Joystick	Pin
Right	Reset
Left	GPIO0(D3)
Up	GPIO12(D6)
Down	GPIO13(D7)
Press	GPIO14(D5)

Onboard LED

There is a green LED at GPIO16(D0).

The green LED at GPIO16(D0) only can be used when there is no need for deep sleep functionality and only can be switched on and off.

In cannot be dimmed using by PWM because GPIO16 is not supporting this.

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

I2C / WIRE Bus

The internally used I2C Bus for the connection with the OLED is not available at a connector. Therefore it is difficult to add more I2C bus devices to this 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 defined in env.json together with the system button and led for configuration. When pressing the joystick while the LED is blinking the device switches to config mode.

{
  "device": {
    "0": {
      "name": "wemos18650",
      "reboottime": "24h",
      "i2c-sda": "D1",
      "i2c-scl": "D2",
      "logfile": 1,
      "led": "D0",
      "button": "D5",
      "description": "ESP8266 board with OLED and 18650"
    }
  },

  "ota": { "0": {} },
  "diag": { "0": {} },
  "ssdp": { "0": { } },

  "DisplaySSD1306": {
    "0": {
      "address": "60",
      "height": 64
    }
  }
}

These are the basic element configurations for the joystick button and the 2 onboard LEDs.

{
  "digitalin": {
    "up":    { "pin": "D6", "title": "Button Up",    "invert": "true", "pullup": "true", "onvalue": "displaytext/up?value=$v"    },
    "down":  { "pin": "D7", "title": "Button Down",  "invert": "true", "pullup": "true", "onvalue": "displaytext/down?value=$v"  },
    "left":  { "pin": "D3", "title": "Button Left",  "invert": "true", "pullup": "true", "onvalue": "displaytext/left?value=$v"  },
    "press": { "pin": "D5", "title": "Button Press", "invert": "true", "pullup": "true", "onvalue": "displaytext/press?value=$v" }
  },

  "displaytext": {
    "up":    { "prefix": "up"    ,  "x": 4, "y": 20 },
    "down":  { "prefix": "down"  ,  "x": 4, "y": 30 },
    "left":  { "prefix": "left"  ,  "x": 4, "y": 40 },
    "press": { "prefix": "press" ,  "x": 4, "y": 50 }
  },

"digitalout": {
    "led": {
      "pin": "D0",
      "invert": "true",
      "value": "0",
      "description": "Builtin LED is on Port D0 = GPIO16"
    }
  },
  "pwmout": {
    "led": {
      "pin": "D4",
      "range": 255,
      "value": 10,
      "invert": "true",
      "description": "Build-in LED on module"
    }
  }
}