---
title: PCF8574 I2C LCD Demo
description: "[![](/qbi/PCF8574 I2C LCD Demo - Parallax_files/I2CLCD-Blue.jpg)](/qbi/PCF8574 I2C LCD Demo - Parallax_files/I2CLCD-Blue.jpg) [![](/qbi/PCF8574 I2C LCD Demo - Parallax_files/I2CLCD-Yellow.jpg)](/qbi/PCF8574 I2C LCD Demo - Parallax_files/I2CLCD-Yellow.jpg) ##### Description The PCF8574 I2C LCD uses just two lines to interface: SDA (serial data) and SCL (serial…"
url: "https://obex.parallax.com/docs/quick-bytes/propeller-2/pcf8574-i2c-lcd-demo/"
updated: "2026-09-29"
category: Propeller 2
---

# PCF8574 I2C LCD Demo

[![](/qbi/PCF8574 I2C LCD Demo - Parallax_files/I2CLCD-Blue.jpg)](/qbi/PCF8574 I2C LCD Demo - Parallax_files/I2CLCD-Blue.jpg) [![](/qbi/PCF8574 I2C LCD Demo - Parallax_files/I2CLCD-Yellow.jpg)](/qbi/PCF8574 I2C LCD Demo - Parallax_files/I2CLCD-Yellow.jpg)

##### Description

The PCF8574 I2C LCD uses just two lines to interface: SDA (serial data) and SCL (serial clock), plus 5VDC and Vss. This LCD, which is available from Parallax with yellow or blue backlight, was extensively demonstrated in the Propeller 2 Live Forum: Spin2 for Beginners Series with JonnyMac. The YouTube video demonstrating the code is linked under Additional Resources. 

Three programs are included in this Quick Byte:

- 02_jm_lcd_pcf8574_demo-Archive.zip (demo shown in the video above, providing a thorough use of the methods in the object);
- 03_jm_lcd_characters-Archive.zip (displays LCD character set with [quadrature encoder](https://www.parallax.com/rotary-encoder/)) 
- 04_jm_lcd_pixels-Archive.zip ([smart pixel control demo](https://www.parallax.com/ws2811-ws2812-ws2812b-ws2813-sk6812x-neopixel-object/) with [quadrature encoder](https://www.parallax.com/rotary-encoder/))

The 02_jm_lcd_pcf8574_demo.spin2 and jm_lcd_pcf8574.spin objects are a complete, documented examples with all of the methods to display text and decimals, position the cursor, control the backlight, etc. 

[PCF8574 I2C LCD Demo Quick Byte](https://www.youtube.com/embed/-SWszMijKpw?feature=oembed)

##### Parts Used

- [P2 Edge Module](https://www.parallax.com/product/p2-edge-module/)
- [P2 Edge Breadboard](https://www.parallax.com/product/p2-edge-module-breadboard/)
- [16x2 I2C LCD Display Module with Yellow Backlight (#26971)](https://www.parallax.com/product/16x2-i2c-lcd-display-module-with-yellow-backlight/)
- [16x2 I2C LCD Display Module with Blue Backlight (#26970)](https://www.parallax.com/product/16x2-i2c-lcd-display-module-with-blue-backlight/)

##### Source Code

- [02_jm_lcd_pcf8574_demo-Archive](/qbi/downloads/02_jm_lcd_pcf8574_demo-Archive-Date-2022.05.23-Time-06.24.zip)
- [04_jm_lcd_pixels-Archive](/qbi/downloads/04_jm_lcd_pixels-Archive-Date-2022.05.23-Time-06.24.zip)
- [03_jm_lcd_characters-Archive](/qbi/downloads/03_jm_lcd_characters-Archive-Date-2022.05.23-Time-06.24.zip)

##### Programming Language

- [Spin 2](https://www.parallax.com/propeller-2/get-started/spin2/)

##### Tools and Operating System

- [Propeller Tool for Windows](https://www.parallax.com/propeller-2/programming-tools/)

##### Additional Resources

- [Propeller 2 Spin Documentation](https://docs.google.com/document/d/16qVkmA6Co5fUNKJHF6pBfGfDupuRwDtf-wyieh_fbqw/edit)
- [Propeller 2 Live Forum Video: JonnyMac Beginner Series Part 3 (YouTube)](https://youtu.be/fxNiDrmbx-s?t=2680)

##### Document Author

- Ken Gracey

##### Source Code Author

- Jon McPhalen