DIP Switches or Microcontroller Based LCD Character Displays

Overview

This project illustrates how the HD44780 LCD displays are driven by DIP switches or an ATmega8 microcontroller.

Details

In the first part, the DIP switches are used to control data bits in order to write characters on LCD. This module uses a 16 character x 2 line display that utilizes a HD44780 compatible ST7065C controller. If the display has a backlight, the last 2 pins (15 & 16) are used but optional. The pin (5) that is tied to the ground is used to control whether writing or reading to the display. The LCD contrast can be controlled by the potentiometer connected to pin 3.

The second part uses an AVR 28-pin development board which utilizes a USB to DC Barrel plug cable for the power supply, eliminating the need for 5V regulator circuit. The barrel connector uses a wire to run to the positive rail. The LCD contrast can be adjusted by adding a trim potentiometer. A piece of wire will also be used to run power to AVCC and will not require an external crystal or AVCC filter block. A 16-pin female header is used for easy LCD removal.