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)
- 04_jm_lcd_pixels-Archive.zip (smart pixel control demo with quadrature 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.