SparkFun 20×4 SerLCD – RGB Backlight (Qwiic)

The SparkFun SerLCD is an AVR-based, serial enabled LCD that provides a simple and cost-effective solution for adding a 20×4 Black on RGB Liquid Crystal Display into your project. We’ve seriously overhauled the PCB design on the back of the screen by including an ATmega328P that handles all of the screen control, meaning a backpack is no longer needed! This display can now communicate in three different ways: serial, I²C, and SPI.

This version comes equipped with a Qwiic connector, bringing serial LCDs into the Qwiic ecosystem. This simplifies the number of wires needed and allows your project to display all kinds of text and numbers.

The onboard ATmega328P AVR microcontroller utilizes 11.0592 MHz crystal for greater communication accuracy with adjustable baud rates of 1200 through 1000000 but is default set at 9600. The firmware for this SerLCD is fully open source and allows for any customizations you may need.

Note: Since the SerLCD is a 3.3V device, please make sure you convert to 3.3V logic depending on your chosen microcontroller or single-board computer. Otherwise, you may risk damaging your board.

Get Started with the Sparkfun SERLCD Guide

Features

• 20×4, Black on RGB Display
• The AVR ATMega328p (with Arduino-compatible bootloader) is populated on the back of each LCD screen and handles all of the LCD control
• Three communication options: Serial, I²C and SPI
• Adjustable I²C address controlled via software special commands (0x72 default)
• Qwiic connection
• Emergency reset to factory settings (Jumper RX to GND on bootup)
• Operational backspace character
• Incoming buffer stores up to 80 characters
• Pulse width modulation of backlight allows direct control of backlight brightness and current consumption
• Pulse width modulation of contrast allows for software-defined contrast amount.
• User-definable splash screen
• Open-sourced firmware and Arduino-compatible bootloader enables updates via the Arduino IDE
• Input voltage: 3.3V-9V (3.3V only via Qwiic connector and “+” pin)
• I/O logic levels: 3.3V
• Current consumption @ 3.3V
  • minimum with no characters
    • 4.5mA (LEDs off)
  • maximum with all character spaces filled
    • 21.7mA (red)
    • 17.2mA (green)
    • 15.5mA (blue)
    • 41.1mA (white)
• Dimensions (LxWxH): 97.67mm x 60.23mm x 15.32mm
• Weight: 0.1532 oz.

Resources

• Hookup Guide

• Firmware Hex File

• GitHub Firmware Repo

• Dimensional Drawings (PDF)

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• Python Support (Qwiic_Py)