i2c / SPI character LCD backpack - STEMMA QT / Qwiic

The Character LCD Backpack is a convenient and easy way to reduce the number of pins required for interfacing with a character LCD, making it ideal for microcontroller projects that need a display without using up all your available pins. By utilizing I2C or SPI input/output expanders, this backpack enables you to control an LCD with just 2 pins (I2C) or 3 pins (SPI), simplifying the wiring while maintaining ease of use. This is perfect for projects where pin limitations are a concern.

Key Features:

• I2C and SPI Interface: Only 2 pins needed for I2C, 3 pins for SPI, greatly reducing the number of pins required to control the display.
• Compatible with Standard Character LCDs: Works with any LCD from 8x1 to 20x4 sizes that have a 16-pin single-line header.
• Pre-Soldered Terminal Blocks: Includes 2-pin and 3-pin terminal blocks for easy wiring to your microcontroller.
• I2C and SPI Libraries: Fully compatible with Arduino and CircuitPython/Python libraries for easy integration and backward compatibility with existing 6-pin wiring setups.
• Boost Circuit: Includes a 3-5V boost circuit to power 5V LCDs even with a 3V power supply.
• Contrast Potentiometer: Features a new, improved potentiometer that’s easier to adjust with a small screwdriver.
• STEMMA QT Connectors: Features SparkFun Qwiic compatible STEMMA QT connectors for simple plug-and-play I2C connections, eliminating the need for soldering the I2C and power lines.

This backpack is an ideal solution for reducing wiring complexity while keeping your project neat and easy to manage. It also comes with improved silkscreen and board design for better clarity. While it works great with standard character LCDs, note that it is not compatible with 16x2 OLED displays or RGB backlight LCDs (though you can still control the digital I/O pins and manage the backlight separately).

For advanced users, the MCP23008 (I2C) offers 8 I/O pins (7 connected) with optional pull-ups, and the SPI 74HC595 provides 7 connected outputs, allowing you to use this backpack for general-purpose I/O expansion as well.

What's Included:

• Assembled backpack board with pre-soldered terminal blocks.
• Updated PCB with an easy-to-read silkscreen and Adafruit Pinguin design for better clarity.

This is a great way to streamline your LCD connections, especially when working with microcontrollers like Arduino or Raspberry Pi, and can help you avoid wasting valuable pins on basic display tasks!