Lcd interfacing with microprocessor 8051

How to interface LCD with Microprocessor 8051

1. LCD Interfacing With 8051 Microprocessor

2. Group Members Hasnain Yaseen EE161021 Sufyan Nasir EE161036 Muhammad Ahtsham EE161012 Usman Ashraf EE161046

3. Introduction LCD display is an inevitable part in almost all embedded projects and this pre is about interfacing a 16×2 LCD with 8051 microcontroller. Many guys take it hard to interface LCD module with the 8051 but the fact is that if you learn it properly, its a very easy job and by knowing it you can easily design embedded projects like Digital voltmeter / ammeter, Digital clock, Home automation displays, Status indicator display, Display for music players etc.

4. Liquid Crystal Diode (LCD) A Liquid Crystal Display (LCD) is a thin , flat panel display device used for electronically displaying information such as text ,images and moving picture. LCD is used in Computer monitors, Televisions , Instrument panels, Gaming devices etc. Polarization of lights is used here to display objects.

5. Why LCD ? Smaller size — LCDs occupy approximately 60 percent less space than CRT displays an important feature when office space is limited. Lower power consumption— LCDs typically consume about half the power and emit much less heat than CRT displays. Lighter weight — LCDs weigh approximately 70 percent less than CRT displays of comparable size. No electromagnetic fields — LCDs do not emit electromagnetic fields and are not susceptible to them. Thus, they are suitable for use in areas where CRTs cannot be used. Longer life — LCDs have a longer useful life than CRTs.

6. 16×2 LCD 16×2 LCD module is a very common type of LCD module that is used in 8051 based embedded projects. It consists of 16 rows and 2Â columns of 5×7 or 5×8 LCD dot matrices. The module were are talking about here is type number JHD162A which is a very popular one . It is available in a 16 pin package with back light ,contrast adjustment function . Each dot matrix has 5×8 dot resolution

7. LCD pin Configuration Pin No: Name  Function 1 VSS This pin must be connected to the ground 2 VCC  Positive supply voltage pin (5V DC) 3 VEE Contrast adjustment 4 RS RS=0 to select command register, RS=1 to select data register 5 R/W R/W=0 for write, R/W=1 for read 6 E  Enable 7 DB0  Data 8 DB1  Data 9 DB2  Data 10 DB3  Data 11 DB4  Data 12 DB5  Data 13 DB6  Data 14 DB7  Data 15 LED+  Back light LED+ 16 LED-  Back light LED-

8. 16×2 LCD module commands Command Function 0F LCD ON, Cursor ON, Cursor blinking ON 01 Clear screen 02 Return home 04 Decrement cursor 06 Increment cursor 0E Display ON , Cursor  blinking OFF 80 Force cursor to the beginning of  1 st  line C0 Force cursor to the beginning of 2 nd line

9. 16×2 LCD module commands 38 Use 2 lines and 5×7 matrix 83 Cursor line 1 position 3 3C Activate second line 08 Display OFF, Cursor OFF C1 Jump to second line, position1 OC Display ON, Cursor OFF C1 Jump to second line, position1 C2 Jump to second line, position2

10. LCD initialization The steps that has to be done for initializing the LCD display is given below and these steps are common for almost all applications. Send 38H (Use 2 lines and 5×7 matrix)to the 8 bit data line for initialization Send 0FH for making LCD ON, cursor ON and cursor blinking ON. Send 06H for incrementing cursor position. Send 01H for clearing the display and return the cursor.

11. Sending data to the LCD The steps for sending data to the LCD module is given below. Make R/W low. Make RS=0 if data byte is a command and make RS=1 if the data byte is a data to be displayed. Place data byte on the data register. Pulse E from high to low. Repeat above steps for sending another data

12. LCD Contrast Control LCD display contrast is adjusted through a variable resistor . A potentiometer is connected between the appropriate power supply rails ( Vdd and Vss for single supply, and Vee and Vdd for higher voltage LCD modules).  The wiper of the pot is connected to Vo (LCD bias voltage input, see below).  The LCD is then positioned at the nominal viewing position, and the pot is adjusted to obtain the desired LCD appearance

13. LCD Timing for Read

14. LCD Timing for Write

15. Interfacing 16×2 LCD with 8051

16. Code for LCD Interfacing ORG 0000 MOV A,#38H ; initialize. LCD 2 lines, 5x7 Matrix. ACALL COMNWRT ; Call command Subroutine ACALL DELAY ; Give LCD some time. MOV A, #0EH ; Display on, cursor on. ACALL COMNWRT ; Call command Subroutine. ACALL DELAY ; Give LCD some time. MOV A, # 01 ; Clear LCD. ACALL COMNWRT ; Call command subroutine ; ACALL DELAY ; Give LCD sometime MOV A, # 06H ; Shift cursor right. ACALL COMNWRT ; ACALL DELAY BACK: MOV A, #82H ; Cursor at line 1 position 2 ACALL COMNWRT ; Call command subroutine. ; ACALL DELAY ; Give LCD some time ; // MESSAGE DISPLY MOV A, #'F' ; Display letter F ACALL DATAWRT ; Call Data command subroutine MOV A, #'A' ; Display letter A ACALL DATAWRT ; Call Data command subroutine MOV A, #'J' ; Display letter J ACALL DATAWRT ; Call Data command subroutine MOV A, #'R' ; Display letter R

17. Code for LCD Interfacing MOV A, #01 ; Clear screen ACALL COMNWRT ; Call Data command subroutine SJMP BACK ; Keep displaying these letters ; AGAIN: SJMP AGAIN COMNWRT: MOV P1, A CLR P3.0; RS=0 FOR COMMAND WRITE CLR P3.1; R/W=0FOR WRITE SETB P3.2; E=1 FOR HIGH PUSLSE CLR P3.2 ;E=0 FOR H-TO-L PULSE RET DATAWRT: MOV P1, A; WRITE DATA TO LCD SETB P3.0; RS=1 FOR DATA CLR P3.1; R/W=0 F0R WRITE SETB P3.2; E=1 FOR HIGH PULSE CLR P3.2; E=0 FOR H-TO-L PULSE RET DELAY: MOV R4, #1 HERE: DJNZ R4, HERE RET END

18. Thank You