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2.4. LCD Character
2 x 16
The LCD Module can easily be used with an 8051 microcontroller such
as the AT89s51. The LCD Module comes with a 16 pin connector. This can
be plugged into connector 16 pin. The pins on the 16 pin connector of
the LCD Module are defined below.

Figure 2.4.1 LCD Character 2 x 16 Module
PIN |
Name |
Function |
1 |
VSS |
Ground voltage |
2 |
VCC |
+5V |
3 |
VEE |
Contrast voltage |
4 |
RS |
Register Select
0 = Instruction Register
1 = Data Register |
5 |
R/W |
Read/ Write, to choose write or read mode
0 = write mode
1 = read mode |
6 |
E |
Enable
0 = start to lacht data to LCD character
1= disable |
7 |
DB0 |
LSB |
8 |
DB1 |
- |
9 |
DB2 |
- |
10 |
DB3 |
- |
11 |
DB4 |
- |
12 |
DB5 |
- |
13 |
DB6 |
- |
14 |
DB7 |
MSB |
15 |
BPL |
Back Plane Light |
16 |
GND |
Ground voltage |
LCD Character
Background
The LCD Character standard requires 3 control lines as well as either
4 or 8 I/O lines for the data bus. The user may select whether the LCD
is to operate with a 4-bit data bus or an 8-bit data bus. If a 4-bit
data bus is used the LCD will require a total of 7 data lines (3 control
lines plus the 4 lines for the data bus). If an 8-bit data bus is used
the LCD will require a total of 11 data lines (3 control lines plus
the 8 lines for the data bus).
The three control lines are referred to as EN,
RS, and RW.
The EN line is called "Enable."
This control line is used to tell the LCD that you are sending it data.
To send data to the LCD, your program should make sure this line is
low (0) and then set the other two control lines and/or put data on
the data bus. When the other lines are completely ready, bring EN high
(1) and wait for the minimum amount of time required by the LCD datasheet
(this varies from LCD to LCD), and end by bringing it low (0) again.
The RS line is the "Register
Select" line. When RS is low (0), the data is to be treated as
a command or special instruction (such as clear screen, position cursor,
etc.). When RS is high (1), the data being sent is text data which sould
be displayed on the screen. For example, to display the letter "T"
on the screen you would set RS high.
The RW line is the "Read/Write"
control line. When RW is low (0), the information on the data bus is
being written to the LCD. When RW is high (1), the program is effectively
querying (or reading) the LCD. Only one instruction ("Get LCD status")
is a read command. All others are write commands--so RW will almost
always be low.
Finally, the data bus consists
of 4 or 8 lines (depending on the mode of operation selected by the
user). In the case of an 8-bit data bus, the lines are referred to as
DB0, DB1, DB2, DB3, DB4, DB5, DB6, and DB7.
An Example Hardware Configuration
As we've mentioned, the LCD requires either 8 or 11 I/O lines to communicate
with. For the sake of this tutorial, we are going to use an 8-bit data
bus--so we'll be using 11 of the 8051's I/O pins to interface with the
LCD.
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Lesson 1:
T
o o l
1.1. Programmer
1.2. Edsim
51
1.3. MIDE-51
1.4. ATMEL
ISP
Lesson 2:
Input Output
2.1.LED
2.2.Swicht
2.3.7
Segmen
2.4.LCD
Character
2.5.ADC
2.6.DAC
2.7.Motor
Stepper
2.8.Keypad
Lesson 3:
Timer Counter
3.1.Basic
3.2.Mode
0
3.3.Mode
1
3.4.Mode
2
3.5.Mode
3
Lesson 4:
Serial Comm.
4.1.Basic
4.2.LED
4.3.Rotate
LED
4.2 ADC
4.3.LCD
Lesson 5:
Interuption
5.1.Basic
5.2.Timer
5.2.External
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