Pololu 16x2 Character LCD with LED Backlight (Parallel Interface)

This 16 x 2 LCD packs 32 characters into an outline smaller than that of most two-line displays. An LED backlight enables optimal viewing in all lighting conditions. This unit uses the HD44780 interface found on most parallel character displays.

Overview

This 16-character, 2-line parallel liquid crystal display achieves a large viewing area in a compact package. It features a yellow-green LED backlight and uses the common HD44780 interface (330k pdf), so sample interface code is widely available for a variety of microcontrollers. This LCD is also available without a backlight.

The DDRAM address 0x00 corresponds to the first character of the top line, address 0x0F corresponds to the last character of the top line, address 0x40 corresponds to the first character of the second line, and address 0x4F corresponds to the last character of the second line.

You can find sample HD44780 LCD interface code written for a variety of AVR microcontrollers as part of the Pololu AVR library.

Pinout

Pin	Symbol	Function
1	Vss	ground (0 V)
2	Vdd	5 V logic supply voltage
3	Vo	contrast adjustment
4	RS	H/L register select signal
5	R/W	H/L read/write signal
6	E	H/L enable signal
7-14	DB0 â€" DB7	H/L data bus for 4- or 8-bit mode
15	A (LED+)	backlight anode
16	K (LED-)	backlight cathode

Using Contrast and the Backlight

As shown in the diagram above, a potentiometer whose output is connected to Vo will allow you to set the contrast for optimal viewing of your display.

The backlight in this LCD is composed of LEDs in series. The total voltage drop across these LEDs is typically 4.2 V and the recommended current through the LEDs is 120 mA. You should use a current limiting resistor R_LIMIT as shown above where:

R_LIMIT = (V_BACKLIGHT â€" 4.2V) / 0.12A

In the diagram above, V_BACKLIGHT is shown as 5 V, but you are not restricted to 5 V; any voltage above the diode-drop voltage will work as long as you choose the appropriate value for your current-limiting resistor. You can also use a PWM-controlled MOSFET to achieve variable dimming of the backlight if so desired.

Note: No cables or connectors are included with this product, but a 40×2-pin 0.100" male header strip and 20", 16-conductor ribbon cable can be purchased separately. You can break a 7×2 segment from the header strip and solder it to the 14 through-holes on the left side of the LCD PCB; the ribbon cable will then plug into the header pins (leaving two holes empty). The header pins wonâ€â„¢t enforce proper orientation of the cable, so you will need to take care to plug it in to the correct pins. The 8×2 shrouded box header will not work with this LCD.

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Dimensions

Size:	85.0 x 29.5 x 13.5 mm
Viewing area:	64.5 x 16.4 mm
Dot size:	0.56 x 0.61 mm
Character size:	3.00 x 5.23 mm
Weight:	35 g

General specifications

Minimum logic voltage:	4.5 V
Maximum logic voltage:	5.5 V
Typical LED backlight voltage drop:	4.2 V
Typical LED backlight current:	120 mA
Supply current:	2 mA

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File downloads

HD44780 interface datasheet(330k pdf)

This document details the HD44780 parallel interface that is an industry standard for dot-matrix LCDs.