TISHITU AVR Studio Atmega LCD Interface with Proteus Simulator
LCD stands for Liquid Crystal Display. It can be used to display anything (virtually anything!). They are of many types. The ones we commonly use for embedded systems, robotics, etc are of two types -- character LCD and graphical LCD. We will discuss about character LCDs in this post whereas graphical LCDs will be discussed later.
The most popular type of character LCD is the HD44780 Character LCD. In this post, we will be using the JHD 162A character LCD shown below.
JHD 162A Character LCD
The JHD 162A LCD is fully compatible with the HD44780 LCD. Hence, the same set of codes will work for both. It is a 16×2 LCD module i.e. it has 16 columns and 2 rows for display. It can operate in either 8 bit mode or 4 bit mode. In 8 bit mode, an 8 bit is data is sent to the LCD from the MCU whereas in 4 bit mode, 4 bits of data are sufficient to operate it.
It has 16 pins, the details of which is given below:
JHD 162A Pin Configuration
Now, for the LCD to work in 8 bit mode, it requires the 8 data pins (DB0...DB7) and 3 control pins (RS, R/W, EN) whereas in 4 bit mode, it requires 4 data pins (DB4...DB7, only the upper nibble) and 3 control pins (RS, R/W, EN). Though the 8 bit mode is faster and more accurate, it consumes more pins of the MCU. However, the 4 bit mode is also fast and accurate enough to satisfy most of our need, plus it requires only 7 pins for interfacing. Hence, we will be working in the 4 bit mode. In the 4 bit mode, data pins DB0...DB3 are left open.
Interfacing LCD
First of all, you need to make basic connections of the LCD. You can refer to the following circuit diagram for this. Relate it with the pin configuration given above.
LCD Connector
Before coding, kindly download the LCD library written by Peter Fleury from here. This is an awesome library with predefined codes so that we can ease out a little bit by not breaking our heads upon the coding part. Thus we get to use the library functions instead of going into the depths of programming. This method is much more productive, efficient and time saving.
Configuring the library
Now that we are ready for programming, open up AVR Studio 5 and create new project. If you are new to AVR Studio 5, view this page to get started. Now in the right pane, you will find the Solution Explorer window. There, right click on the project name, go to Add and then choose Existing Item.... Now browse to the folder where you have downloaded the libraries and choose lcd.c and lcd.h.
Adding Libraries
Added Files and Headers
Now you can find the two files (the c file and the header file) listed in your project. Now follow the following steps in order to configure the library.
Double click on the 'lcd.h' file (in the Solution Explorer) to open it. Now make sure that you scroll down very slowly or else you will miss out on some important details.
As you begin to scroll down, you will find some commented text describing the library. Note the line where it says LCD_
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