An application of 8085 register interfacing with LCD
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This document discusses the interfacing of a 20x2 LCD display with the 8085 microprocessor, detailing hardware connections, control signals, and operational modes. It explains the roles of the driver HD44780, data bus configuration, and the handling of read/write operations. Additionally, it covers the software instructions needed for proper setup and data display on the LCD.
![Presented By:-
Taha Malampattiwala
140050107052
CSE 1 [Batch 4]](https://image.slidesharecdn.com/anapplicationof8085registerinterfacingwithlcdsclasnv-160809072534/85/An-application-of-8085-register-interfacing-with-LCD-2-320.jpg)
An application of 8085 register interfacing with LCD
- 1. AN APPLICATION OF 8085 REGISTER INTERFACING WITH LCD
- 2. Presented By:- Taha Malampattiwala 140050107052 CSE 1 [Batch 4]
- 3. INTERFACING LCD • Hardware • 20 x 2-line LCD display • Two lines with 20 characters per line • LCD has a display Data RAM • Stores data in 8-bit character code • Each register in Data RAM has its own address • Corresponds to its position on the line • Line 1 is 00H to 13H • Line 2 is 40H to 53H 3
- 5. INTERFACING LCD •Driver HD44780 •8-bit data bus (RD7-RD0) •Three control signals • RS – Register Select (RA3) • R/W – Read/Write (RA2) • E – Enable (RA1) •Three power connections • Power, ground, and variable resistor to control brightness 5
- 6. INTERFACING LCD •Can be interfaced either in 8-bit mode or 4-bit mode •In 8-bit mode, all eight data lines are connected •In 4-bit mode, only four data lines are connected • Two transfers per character (or instruction) are needed •Driver has two 8-bit internal registers •Instruction Register (IR) to write instructions to set up LCD • Table 9-3 6
- 7. INTERFACING LCD •LCD Operation •When the MPU writes an instruction to IR or data to DR, the controller: •Sets DB7 high indicating that the controller is busy •Sets DB7 low after the completion of the operation •The MPU should always check whether DB7 is low before sending an instruction 7
- 8. INTERFACING LCD •Writing to or Reading from LCD (Table 9-4) •The MPU: •Asserts RS low to select IR •Asserts RS high to select DR •Reads from LCD by asserting the R/W signal high •Writes into LCD by asserting the R/W signal low 8
- 9. INTERFACING LCD • Timing diagram: writing to LCD 9
- 10. INTERFACING LCD •Software • To write into the LCD • Send the initial instructions to set up the LCD • 4-bit or 8-bit mode • Continue to check DB7 until it goes low • Write instructions to IR to set up LCD parameters • Number of display lines and cursor status • Write data to display a message 10