Display

Since 2023, the esieabot is equipped with a small monochrome OLED screen of less than 1 inch diagonal. This screen is connected to the I2C bus of the Raspberry Pi.

../../_images/oled.png

Specifications

Characteristic

Value

Controller

SSD1306

Resolution

128x64 pixels

I2C Address

0x3C

Power Supply

3.3V

More information about the controller: https://www.solomon-systech.com/product/ssd1306/

Connections

The screen is connected as follows:

  • VCC to the 3.3V of the Raspberry Pi

  • GND to the ground of the Raspberry Pi

  • SDA to SDA

  • SCL to SCL

The add-on board is not necessary to connect the screen.

Usage

By default, a built-in service named esieabot-display uses the screen to display various information.

../../_images/screenshot.png

On this display, you will find:

  • The name of the esieabot

  • The battery level

  • The charging status

  • The battery voltage

  • The current being used, when it is positive, it means the battery is charging

  • The connected Wi-Fi network, its IP address, and the signal strength

  • 2 lines of free text

Displaying Text

To display a message on the screen on the 2 lines of free text, simply call the following API:

curl "http://localhost:5090/write?line1=Hello&line2=World"

To display a message on the screen without console messages:

curl "http://localhost:5090/write?line1=Hello&line2=World" > /dev/null

Note

This command must be called from the esieabot itself.

Note

To display special characters (including spaces), it is necessary to encode them in URL. More information about URL encoding: https://www.w3schools.com/tags/ref_urlencode.ASP

Warning

Currently, UTF-8 characters are not supported.