LCD interfacing
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The document summarizes information about liquid crystal displays (LCDs), including: - LCDs are replacing LED displays due to declining prices, ability to display text/graphics, and ease of programming text/graphics. - It describes the pin connections and functions of an LCD, including power supply pins, data/command selection pins, data bus pins, and enable pin. - It provides notes on programming an LCD, including using the busy flag pin to check if the LCD is busy before writing data.
LCD interfacing
- 1. PREPARED BY:- ROBOTICS CLUB
- 2. PREPARED BY:- ROBOTICS CLUB Liquid Crystal Display (LCD):- LCD is finding widespread use replacing LEDs because The declining prices of LCD The ability to display numbers, characters and graphics Ease of programming for characters and graphics
- 3. PREPARED BY:- ROBOTICS CLUB Liquid Crystal Display (LCD):-
- 4. PREPARED BY:- ROBOTICS CLUB Liquid Crystal Display (LCD):-
- 5. PREPARED BY:- ROBOTICS CLUB Pin Descriptions for LCD Pin Symbol I/O Descriptions 1 VSS ----- Ground 2 VCC ----- +5 v power supply 3 VEE ----- Power supply to contrast 4 RS I Register Select( 0 for command register and 1 for data register) 5 __ R /W I 1 for Read 0 for write 6 E I/O Enable 7-14 DB0-DB7 I/O The 8-bit data bus 15 LED + ----- Usually Connected t0 +5v of power supply 16 LED- ----- Connected to Ground
- 6. PREPARED BY:- ROBOTICS CLUB Some Points to note while Programming A high to low pulse should be provided in an enable pin for Write Operation A low to high pulse should be provided in an enable pin for Read Operation Bit D7 of LCD is busy flag which can be used to check if LCD is busy in its own internal operation Busy flag can be read when R/W =1 and RS=0 and a L to H pulse in enable pin NOTE:- It is recommended to check busy flag before writing any data to LCD.
- 7. PREPARED BY:- ROBOTICS CLUB LCD Command Codes Code (Hex) Command to LCD Instruction Register 1 Clear display screen 2 Return home 4 Decrement cursor (shift cursor to left) 6 Increment cursor (shift cursor to right) 5 Shift display right 7 Shift display left 8 Display off, cursor off A Display off, cursor on C Display on, cursor off E Display on, cursor blinking off F Display on, cursor blinking
- 8. PREPARED BY:- ROBOTICS CLUB CONTINUED….. Code (Hex) Command to LCD Instruction Register 10 Shift cursor position to left 14 Shift cursor position to Right 18 Shift the entire display to the left 1C Shift the entire display to the Right 80 Force cursor to beginning to 1st line C0 Force cursor to beginning to 2nd line 38 2 lines and 5x7 matrix