i2c / SPI character LCD backpack - STEMMA QT / Qwiic

The Character LCD Backpack is an add-on circuit that makes it easier to integrate character LCDs into your microcontroller projects. It's perfect for projects that need a simple display without consuming a lot of I/O pins. By using I2C and SPI input/output expanders, this backpack reduces the pin count to just 2 pins for I2C or 3 pins for SPI, freeing up your microcontroller for other tasks.

Key Features:

• Easy to Use: This backpack works with standard 16-pin character LCDs, from 8x1 to 20x4 sizes, making it versatile for various display needs. It is backward compatible with projects using the traditional 6-pin wiring and includes pre-soldered 2-pin and 3-pin terminal blocks for easy connection.
• Compatible with Arduino & CircuitPython: Whether you're using an Arduino or CircuitPython, we've created an easy-to-use library that simplifies integration.
• Not Compatible with OLEDs: While it works perfectly with standard character LCDs, the backpack does not support 16x2 OLED displays. It can work with RGB 16x2 or 20x4 LCDs, but only for controlling the 14 digital I/O pins (pins #1-14); RGB backlighting requires additional wiring.

Recent Updates:

• Boost Circuit: A 3-5V boost circuit has been added, allowing you to control 5V LCDs even when using 3V power and logic.
• Improved Contrast Potentiometer: The contrast potentiometer has been upgraded for easy adjustment with a small screwdriver.
• STEMMA QT Connectors: Added SparkFun qwiic-compatible STEMMA QT connectors for I2C, making it even easier to interface with microcontrollers. Simply use a STEMMA QT adapter cable for a solderless connection (cable sold separately).
• Drop-in Replacement: The backpack’s functionality, size, and shape remain the same, so it’s a drop-in replacement with no code changes required.
• Updated Silkscreen: The updated PCB now features a clear and legible silkscreen, making assembly and use even easier.

Advanced Usage:

• General-Purpose I/O Expansion: Advanced users can repurpose the backpack for general-purpose I/O expansion. The MCP23008 I/O expander offers 8 I/O pins (7 connected) with optional pull-ups, and the SPI 74HC595 provides 7 connected outputs.

This Character LCD Backpack is a must-have for anyone looking to simplify their LCD project setup and free up microcontroller pins for other tasks.