Ecological Succession. ( ECOSYSTEM, B. Pharmacy, 1st Year, Sem-II, Environmen...
ARM LCD Interfacing
1. ARM LPC2148 Training
Class - 2
Topic : Introduction to 16x2
LCD, Interfacing with ARM
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2. Topics
• 16x2 LCD Introduction
• Initialization of LCD
• Simulation of LCD
• Interfacing LCD with ARM
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4. 16x2 LCD Introduction (Cont..)
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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
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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.
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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
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Fig : 4 Code Maps, the Character Code
8. 16x2 LCD Introduction (Cont..)
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Fig : 5 Character Map for 5x8 Fig : 6 Character Map for 5x10
9. 16x2 LCD Introduction (Cont..)
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Fig : 7 ASCII Character Table
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
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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.
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16. Initialization of LCD
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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
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21. Assignment
• Write the program to display “ARM” in LCD and
scroll left by 2 times and right by 2 times.
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