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This 16x 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.
See datasheet on the HD44780 under the downloads tab.
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.
Pin Symbol Function
1 Vss ground (0 V)
2 Vdd power (4.5 to 5.5 V)
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 to DB7 H/L data bus for 4- or 8-bit mode
A LED+ 4.2 V for backlight
K LED- 0 V for 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 RLIMIT as shown above where:
RLIMIT = (VBACKLIGHT 4.2V) / 0.12A
In image 3 above, VBACKLIGHT 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.