Web Site: www.parallax.com Office: (916) 624-8333 Forums: forums.parallax.com Fax: (916) 624-8003 Sales: sales parallax.com Sales: (888) 512-1024 Technical: support parallax.com Tech Support: (888) 997-8267 Parallax Serial LCD 2 rows x 16 characters, Non-backlit, with Piezospeaker ( 27976) 2 rows x 16 characters, Backlit, with Piezospeaker ( 27977) 4 rows x 20 characters, Backlit, with Piezospeaker ( 27979) The Parallax Serial LCDs are very functional, low-cost liquid crystal displays that can be easily interfaced to and controlled by a microcontroller using a 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 with a single instruction and turn the display on and off in any configuration. They support visible ASCII characters Dec 32-127, and in addition you may define up to eight of your own custom characters to display anywhere on the LCD. NOTE: If your Serial LCD Display does not have a speaker on the back, use the specifications and information in the Product Change Notice: Revision E and Earlier section on page 11. Features Clear 40-pixel characters (8 H x 5 W) Supports ASCII DEC characters 32-127 Define up to eight custom characters Automatic text wrapping Single command cursor placement Single command clears the display Define up to eight custom characters Select 2400, 9600, or 19,200 baud with switches on the back of the device Display type: STN, YG, positive transflective LCD Adjustable contrast knob on the back of the device YG LED for backlit model displays Key Specifications Power requirements: o Non-backlit: +5 VDC, 20 mA o Backlit: +5 VDC, 20 mA (light off), ~ 80 mA typical (light on) Communication: Selectable asynchronous serial baud rates: 2400, 9600, 19200 Operating temperature: -4 to +158 F (-20 to +70C) Dimensions: NOTE - Board and LCD size and style may vary o 2x16: Approx. 1.42 x 3.15 in (36 x 80 mm) o 4x20: Approx. 2.37 x 3.86 in (60.2 x 98.1 mm) Copyright Parallax Inc. Parallax Serial LCDs ( 27976, 27977, 27979) v3.1 3/11/2013 Page 1 of 11 Quick-Start Circuit The Serial LCDs should be powered from an external regulated 5 V power supply. Make sure the power supply has an adequate current rating to power the Serial LCD and the BASIC Stamp, Propeller chip, or whichever microcontroller and other devices you are using. CAUTION DO NOT PROVIDE A SIGNAL TO THE RX PIN BEFORE APPLYING 5 VDC TO THE 5V PIN. Baud Rate Setup After connecting the Serial LCD, you will need to select the baud rate at which you are going to send it data. You have three choices: 2400, 9600, and 19,200 baud. To set the baud rate, move the dip switches on the back of the LCD into the correct positions according to the table next to the switches, which is also repeated below: MODE SW1 SW2 Test OFF OFF 2,400 ON OFF 9,600 OFF ON 19,200 ON ON As you can see from the table, there is also a fourth choice called Test. Use this Test mode to confirm that the power and ground to the LCD are hooked up correctly before you send it any data. Move the dip switches to the Test setting and turn on the power. The LCD display should turn on with the backlight on (models 27977, 27979) and display the following text: Parallax, Inc. www.parallax.com If you dont see the text at first, try adjusting the LCD contrast by turning the pot labeled Increase Contrast with a screwdriver. Turn it in the direction of the arrow to make the characters show up more clearly. If you still dont see the characters, go back and check your electrical connections and try again. Once youve successfully completed test mode, move the dip switches to the correct positions to select the baud rate you want to use for your application. Copyright Parallax Inc. Parallax Serial LCDs ( 27976, 27977, 27979) v3.1 3/11/2013 Page 2 of 11