This document discusses interfacing a 16x2 LCD with an ARM processor. It begins with an introduction to 16x2 LCDs, describing their pinout, display data RAM (DDRAM), character generator ROM (CGROM), character generator RAM (CGRAM), and control flags. It then covers initializing the LCD in both 4-bit and 8-bit modes through sending a sequence of commands. The document demonstrates initializing and sending data to the LCD. It concludes with briefly mentioning interfacing the LCD with ARM and providing an assignment to display and scroll text on the LCD.

1. ARM LPC2148 Training
Class - 2
Topic : Introduction to 16x2
LCD, Interfacing with ARM
4/29/2020 Electrical Product Development
Lab
1

2. Topics
• 16x2 LCD Introduction
• Initialization of LCD
• Simulation of LCD
• Interfacing LCD with ARM
4/29/2020 Electrical Product Development
Lab
2

3. 16x2 LCD Introduction
4/29/2020 Electrical Product Development
Lab
3
Fig : 1 PIN Diagram of 16x2 LCD

4. 16x2 LCD Introduction (Cont..)
4/29/2020 Electrical Product Development
Lab
4
Control blocks in LCD
• DDRAM - Display Data RAM
Display data RAM (DDRAM) stores display
data represented in 8-bit character codes. So
whatever you send on the DDRAM is actually
displayed on the LCD
Fig : 2 DDRAM addresses of 4 Line LCDs.

5. 16x2 LCD Introduction (Cont..)
• CGROM- Character Generator ROM
When we send a ASCII value to DDRAM,
how the character is displayed on LCD? so the
answer is CGROM.
The character generator ROM generates 5 x 8
dot or 5 x 10 dot character patterns from 8-bit
character codes.
It can generate 208 5 x 8 dot character
patterns and 32 5 x 10 dot character patterns
4/29/2020 Electrical Product Development
Lab
5

6. 16x2 LCD Introduction (Cont..)
• CGRAM - Character Generator RAM
As clear from the name, the CGRAM area is used to
create custom characters in LCD.
4/29/2020 Electrical Product Development
Lab
6
Fig : 3 CGRAM addresses of 16x2 LCD

7. 16x2 LCD Introduction (Cont..)
• As you can see in both the code maps, the
character code from 0x00 to 0x07 is occupied
by the CGRAM characters or the user-defined
characters.
• If a user wants to display the fourth custom
character then the code to display it is 0x03
4/29/2020 Electrical Product Development
Lab
7
Fig : 4 Code Maps, the Character Code

8. 16x2 LCD Introduction (Cont..)
4/29/2020 Electrical Product Development
Lab
8
Fig : 5 Character Map for 5x8 Fig : 6 Character Map for 5x10

9. 16x2 LCD Introduction (Cont..)
4/29/2020 Electrical Product Development
Lab
9
Fig : 7 ASCII Character Table

10. 16x2 LCD Introduction (Cont..)
4/29/2020 Electrical Product Development
Lab
10
Fig : 8 Extended ASCII Codes

11. 16x2 LCD Introduction (Cont..)
• BF - Busy Flag
– BF =1 Instruction has being executing
– BF = 0 Instruction is executed successfully
• Instruction Register (IR) and Data Register
(DR) 16 BIT
– IR – 8 Bit
– DR – 8 Bit
4/29/2020 Electrical Product Development
Lab
11

12. Initialization of LCD
• Two different modes of configuration
– 8 Bit mode
• Operates fast because the data is transferred by
single Enable pulse on EN pin.
• Requires more data lines
– 4 Bit mode
• Requires less data lines
• Operates slow because the data is transferred after
two Enable pulse on EN pin.
4/29/2020 Electrical Product Development
Lab
12

13. Initialization of LCD
4/29/2020 Electrical Product Development
Lab
13
Fig : 9 Connection diagram of 16x2 LCD

14. Initialization of LCD
4/29/2020 Electrical Product Development
Lab
14
Fig : 10 16x2 LCD Commands

15. D4 D5 D6 D7
1 1 0 0
1 1 0 0
1 1 0 0
0 1 0 0
4/29/2020 Electrical Product Development
Lab
15
Fig : 11, 4-Bit mode Initialization Procedure
Table 1: Initialization
Step

16. Initialization of LCD
4/29/2020 Electrical Product Development
Lab
16
D4 D5 D6 D7
1 1 0 0
1 1 0 0
1 1 0 0
0 1 0 0
0 1 0 0
0 0 0 1
0 0 0 0
1 1 1 1
Table 1: Initialization Step
As mention in datasheet
Function set 4 Bit mode
2 line 5x7 Dots
HEX value – 0x28
Display ON Cursor Blink
HEX value – 0x0F
Passing Command
RS – Register Select
• 0 to pass command
• 1 to pass data
RW – Read/Write
• 0 to Write LCD
• 1 to Read LCD
1. Send Hex Command
• 4 bit binary data to D7
to D4
• CLK from 0 to 1 at E
pin
• .
.

17. Initialization of LCD
Passing Data to LCD
• RS – Register Select
• 0 to pass command
• 1 to pass data
• RW – Read/Write
• 0 to Write LCD
• 1 to Read LCD
• Display ‘A’ in LCD
• Send upper 4 bit 0100
• CLK E pin from 0 to 1 →0
• Send lower 4 bit 0001
• CLK E pin from 0 to 1 →0
4/29/2020 Electrical Product Development
Lab
17

18. Initialization of LCD
4/29/2020 Electrical Product Development
Lab
18
Fig : 12, 4-Bit and 8- Bit mode data flow

19. Simulation of LCD
4/29/2020 Electrical Product Development
Lab
19

20. Interfacing LCD with ARM
4/29/2020 Electrical Product Development
Lab
20

21. Assignment
• Write the program to display “ARM” in LCD and
scroll left by 2 times and right by 2 times.
4/29/2020 Electrical Product Development
Lab
21

22. Thank You
4/29/2020 Electrical Product Development
Lab
22