In many microcontroller applications some sort of display is needed to present information and status of the controller to the user. Although a few LEDs can provide a lot of information, a more advanced display is sometimes needed. A solution which is quite often seen is using a HD44780-based character LCD module. These modules come in various configurations from one line of 8 chars to 4 lines of 40 characters.
Implement HD44780-based LCDs With AVR Microcontrollers: [Link] - [via]
The PIC 16F876A drives a standard LCD module with a HD44780 controller and a resolution of two rows of 16 characters each. The HD44780 requires 8 data lines (port B of the 16F876A) and three control signals: RegisterSelect (RC6), Read/Write (GND) and Enable (RC7). Since the data presented on the 8-bit-wide output port RB0-7 is only written to the HD44780, the R/W input is hardwired to ground (/Write). The LCD back-light LEDs are supplied through two 10ohm current-limiting resistors.
RF-Microwave Frequency Counter: [Link]
Connecting a LCD display to the end of a printer-cable is a simple and effective way of providing additional functionality to your computer system. The printer-cable LCD can be mounted on your computer case or fitted inside a Jiffy-Box and displayed somewhere away from your case. Even the fully functional software interface is simple to install and configure. The parts used are a non-backlit 16 x 2 character LCD and a parallel port cable(printer cable).
LCD Display Controlled From A Computer Trough The Parallel Port: [Link]
LCD2USB is a open source/open hardware project. The goal of LCD2USB is to connect HD44780 based text LCD displays to various PCs via USB. LCD2USB was meant to be cheap and to be made of easily available parts. It is therefore based on the Atmel AVR Mega8 CPU and does not require any difficult to obtain parts like separate USB controllers and the like. The total cost (without display and pcb) are about 5 to 10 Euros. LCD2USB currently comes with a simple demo application that works under Linux, MacOS X and Windows.
HD44780 LCD Connected To USB: [Link]
Adding a cheap LCD to your PC is a popular diy project for many beginners in electronics. The parallel port however, is dead. It’s obsolete. It’s big…ugly and just awful. The solution? Add a USB interface to your existing LCDs. The circuit interfaces to a standard HD44780 compatible LCD and emulates the CrystalFontz serial protocol over a virtual COM port created by the FTDI chip. This enables you to use already existing software to speak to the LCD, for example the popular program LCD Smartie. The circuit uses an AVR microcontroller, the Atiny2313, and a USB chip from FTDI. The usb chip creates a virtual COM port on the computer. It has an external EEPROM programmable via USB to store information and settings. You can for example have the chip report back the name of your project when you plug it in. Very neat.
The backlight and contrast can be controlled from the computer. They are each connected to one of the PWM outputs on the AVR. Since the CrystalFontz protocol support software control of contrast and backlight, this seemed like a nice feature to add. Only LED backlights are supported, no EL backlights. The backlight can be powered from the USB port if its current draw is less than about 420 mA. If you need more, an external supply can be connected.
LCD USB interfacing: [Link]
