Vishwakarma government engineering college Prepare by. Hardik Jolapara( ) LCD Interfacing with ATmega16

Concept  LCD is used to provide textual information from microcontroller.  It makes the applications in microcontroller more interactive.  LCD comes in various configurations such as 20 x 2, 16 x 1, 40 x 1, 16 x 2 etc.  Out of these, 16 x 2 is widely used. LCD also has a microcontroller in it.  This microcontroller is already coded to display characters on the screen.  Now we have to send the data to this LCD through our microcontroller by following the given steps

LCD(16*2)  The LCD can be used as 8-bit interface or 4- interface.  In this tutorial I am using 8-bit interface. The whole of PORTB is connected to pins 7-14 of LCD. LCD has three control Pins namely Enable (En is pin 6), Read/Write (RW is pin 5) and Register Select (RS is pin 4).  Writing data or commands on the LCD registers can happen only on the falling edge of the En. So, before sending any command or data  When RW is HIGH, we can read from LCD and when RW is LOW we can print on LCD. Since we want to only print on LCD we can simply Ground the RW pin.  When RS is HIGH, we need to send the character’s value in PORTB and when RS is LOW we need to send the command’s value in PORTB.  So now that we have understood the functioning of LCD, we can move to the coding part of it

AVR Atmega16

Interfacing of AVR & LCD

Hardware required  AVR Trainer Board-100-1pc  AVR USB Programmer-1pc  12V, 1A DC Adapter-1pc  16X2 Alphanumeric LCD(JHD162A)-1pc  1 to 1 Connector-3pcs  10 to 10 FRC Female Connector-2pcs

Connection guide  The step-by-step connection guide for 16X2 Alphanumeric LCD Interfacing with ATmega16 project is as follows:  Insert the DC Pin of 12V, 1A DC Adapter to the DC Socket of AVR Trainer Board-100.  Connect PortB header with LCD data header in AVR Trainer Board-100 with a 10 to 10 FRC Female Connector.  Connect RS, RW & EN pins of LCD control header with PD0, PD1 & PD2 pins of PortD header respectively in AVR Trainer Board-100 with 1 to 1 Connectors.  Connect the 16X2 Alphanumeric LCD to the LCD header of AVR Trainer Board-100.

 Connect the ISP header of AVR Trainer Board-100 with AVR USB Programmer header of AVR USB Programmer with a 10 to 10 FRC Female Connector.  Connect the AVR USB Programmer to the PC/Laptop’s USB Port directly or with the help of USB AM-FM Cable.  Switch on the power with the help of Power Switch of AVR Trainer Board  Download the 16X2 Alphanumeric LCD Interfacing with ATmega16 Hex file to AVR Trainer Board-100 with the help of SinaProg Hex downloader and AVR USB Programmer.  See the output.

Code for LCD  For LCD we require only three primary functions LCD_cmd(), LCD_write() and main() void LCD_cmd(unsigned char cmd); This function takes a character as input which it initialises to PORTB keeping the value or RS LOW (since, we want to send a command).  void LCD_write(unsigned char data); This function to display the character which is taken as input. It should be noted that while displaying the value of RS is HIGH.  Now, either you learn the commands required for the LCD and initialize the LCD using those commands in the main or you can use the functions which I have provided in my code. The Full LCD code is given below. It has many functions which would be useful. The details about the function is given in comments in each function

Working of interfacing  LCD (Liquid Crystal Display) screen is an electronic display module and find a wide range of applications.  These modules are preferred over seven segments and other multi segment LEDs.  When you start working with LCD modules you will start feeling the real power of MCU and your imaginations will be touching sky.  The alphanumeric LCD that we are going to interface is a 16X2 alphanumeric LCD. It means the LCD can display 16 characters in each row and it has two rows. It is a HD44780 controller based LCD.  There are two methods to interface any alphanumeric LCD with AVR ATmega16 microcontroller: 8-bit and 4-bit interfacing method.

 In 8-bit interfacing method, all the eight data pins of the alphanumeric LCD are used and in 4-bit interfacing method, only the upper 4 data pins (D4, D5, D6 and D7) of the alphanumeric LCD are used to send 8-bit data (or command) to the alphanumeric LCD from the microcontroller  In 8-bit method, the 8-bit data (or command) is sent at a time using the 8 data lines of the alphanumeric LCD but in 4-bit method, the 8-bit data (or command) cannot be sent at a time to the alphanumeric LCD. So, the upper 4 bits of data (or command) are sent first and the lower 4 bits are sent later.  In this project, we will learn How to interface a 16X2 alphanumeric LCD with AVR ATmega16 microcontroller using 8-bit interfacing method. Here, we will display “ABLab Solutions” in 1st row and “ in 2nd row of the 16X2 alphanumeric LCD

Programming in ‘C’  //**************************************************************// //System Clock :1MHz //Software :AVR Studio 4 //LCD Data Interfacing :8-Bit //**************************************************************//  #include /*Includes io.h header file where all the Input/Output Registers and its Bits are defined for all AVR microcontrollers*/  #define F_CPU /*Defines a macro for the delay.h header file. F_CPU is the microcontroller frequency value for the delay.h header file. Default value of F_CPU in delay.h header file is (1MHz)*/  #include /*Includes delay.h header file which defines two functions, _delay_ms (millisecond delay) and _delay_us (microsecond delay)*/  #define LCD_DATA_PORT PORTB /*Defines a macro for the lcd.h header File. LCD_DATA_PORT is the microcontroller PORT Register to which the data pins of the LCD are connected. Default PORT Register for data pins in lcd.h header file is PORTA*/

 #define LCD_CONT_PORT PORTD /*Defines a macro for the lcd.h header File. LCD_CONT_PORT is the microcontroller PORT Register to which the control pins of the LCD are connected. Default PORT Register for control pins in lcd.h header file is PORTB*/  #define LCD_RS PD0 /*Defines a macro for the lcd.h header file. LCD_RS is the microcontroller Port pin to which the RS pin of the LCD is connected. Default Port pin for RS pin in lcd.h header file is PB0*/  #define LCD_RW PD1 /*Defines a macro for the lcd.h header file. LCD_RW is the microcontroller Port pin to which the RW pin of the LCD is connected. Default Port pin for RW pin in lcd.h header file is PB1*/  #define LCD_EN PD2 /*Defines a macro for the lcd.h header file. LCD_EN is the microcontroller Port pin to which the EN pin of the LCD is connected. Default Port pin for EN pin in lcd.h header file is PB2*/  #include /*Includes lcd.h header file which defines different functions for all Alphanumeric LCD(8-Bit Interfacing Method). LCD header file version is 1.1*/

 int main(void) {  DDRB=0xff; /*All the 8 pins of PortB are declared output (data pins of LCD are connected)*/  DDRD=0x07; /*PD0, PD1 and PD2 pins of PortD are declared output (control pins of LCD are connected)*/  char first_row_lcd_display[] =”ABLab Solutions”, second_row_lcd_display[]=” /*Variable declarations*/  lcd_init(); /*LCD initialization*/  lcd_string_write(first_row_lcd_display); /*String display in 1st row of LCD*/  lcd_command_write(0xc0); /*Cursor moves to 2nd row 1st column of LCD*/  lcd_string_write(second_row_lcd_display); /*String display in 2nd row of LCD*/  }

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