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Parallax 4 x 20 Serial LCD with Piezospeaker (Backlit)

  • 27979 Parallax 4x20 Serial LCD (Backlit)
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$13.00 (30%)
Product ID: 27979
In Stock: 75


The Parallax Serial LCDs (liquid crystal displays) can be easily connected to and controlled by a microcontroller using single I/O pin. The LCD displays provide basic text wrapping so that your text looks correct on the display. Full control over all of their advanced LCD features allows you to move the cursor anywhere on the display or control the piezospeaker with a single instruction and turn the display on and off in any configuration. They support visible ASCII characters Dec 32-127.  In addition, you may define up to eight of your own custom characters to display anywhere on the LCD.

Key Features:

  • Clear 40-pixel characters support ASCII DEC 32-127
  • Turn backlighting on or off with a single command
  • Eight user-definable custom characters
  • Move the cursor anywhere or clear the display with a single command
  • Built-in piezospeaker lets you add audible alert tones
  • Baud mode selector and adjustable contrast on the back of the display

Application Ideas:

  • Professional-looking text user interface on any microcontroller application
  • Easy serial debugging without a PC
  • Real-time sensor data output on autonomous robot


  • 4 rows x 20 characters
  • Built-in piezospeaker
  • Test mode verifies display functionality
  • Adjustable contrast knob
  • Baud rate switches on back of device
  • Power requirements: +5 VDC, 20 mA (light off), ~80 mA typical (light on)
  • Selectable asynchronous serial baud rates: 2400, 9600, 19200
  • Dimensions: 2.37 x 3.86 in (60.2 x 98.1 mm)
  • Operating temp range: -4 to +158 °F (-20 to +70 °C)


  • The LCDs currently for sale are updated to Revision F. Basic functionality remains the same, but power requirements and the layout of the backpack have changed. Please see the documentation for information on your model.
  • This device can be connected to a PC serial port using a MAX232 line driver. The circuit isn't supported by Parallax, but it's possible to make this connection with a few extra parts.

Downloads & Documentation

Product Specific Downloads
Download Details More Info
Propeller C Learn Folder - 10.07 MB | updated: 02 Mar 2020 - 5:24 pm
Smart Sensors and Applications Text - 4.51 MB | updated: 12 Sep 2013 - 11:21 am
Parallax Serial LCD SXB Example Code - 2.2 KB | updated: 26 Sep 2012 - 8:56 am
Parallax Serial LCD Javelin Stamp Example Code - 5.23 KB | updated: 26 Sep 2012 - 8:53 am
Parallax Serial LCD Propeller P8X32A Example Code - 853 bytes | updated: 26 Sep 2012 - 8:50 am
Parallax Serial LCD BASIC Stamp Example Code - 7.79 KB | updated: 26 Sep 2012 - 8:48 am
Parallax Serial LCD Product Guide - 128.87 KB | updated: 11 Mar 2013 - 10:43 am

Additional Resources