Parallax 4 x 20 Serial LCD with Piezospeaker (Backlit)

SKU 27979 Categories , ,


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Product Description

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.

Additional Information

Weight 0.2052 lbs
Dimensions 1 × 1 × 1 in



Resource Links

Half-Duplex Serial Tutorial – Propeller C (Learn.Parallax)

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Last edited 2 months ago by Vinay
Stephanie Lindsay

The LCD you linked to is a 4-pin device with an I2C interface, requiring 2 I/O pins. The Parallax Serial LCD is a 3-pin device with a simple serial interface, requiring only one I/O pin. There is a 2×16 Serial LCD Kickstart archive on this page that includes starter Arduino code for communicating with Parallax Serial LCDs. The documentation for the Parallax Serial LCDs under the Downloads tab explains the command set for all the Parallax Serial LCDs; the 2×16 just uses a subset.