Simply to explain the working principle
of our 5x7 Led Dot Matrix Panel we introduced the one block/segment operation
of this 5x7 Led Dot Matrix Panel. Thus we will understand the functionality of
different Integrated Circuits pins and how different logic are passing through that pins. We
also observed the decorder/demultiplexer‘s and octal buffer/line driver‘s logic
variation at instant of time in simulation.
The simple Proteus simulation block
diagram of this is as shown in Fig.12a
Fig.12a
Here we used the common anode 5x7 Led
Dot Matrix Module. Thus we applied the +Vcc or high logic to the row and ground
or low logic to the column of 5x7 Led Dot Matrix Module.
In Micro-controller we used Port0 as a selection of column to providing ground or logic low and Port2 providing data bus to the row of 5x7 Led Dot Matrix Module.
For that concept we make the data code of the character ‘A’ which write as below.
In Micro-controller we used Port0 as a selection of column to providing ground or logic low and Port2 providing data bus to the row of 5x7 Led Dot Matrix Module.
For that concept we make the data code of the character ‘A’ which write as below.
Unsigned array column = {0x7Eh,
0x7Dh, 0x7Bh, 0x77h, 0x6Fh}
Unsigned array row = {0x81h,
0xF6h, 0xF6h, 0xF6h, 0x81h}
When micro-controller is sending the 0x7Eh data at Port0 at that time micro-controller is also sending 0x81h data at Port2. This both data are synchronized to each other. This are Shown in Fig. This synchronization is always in same manner to all five data of the array.
Fig.12b
The 0x81h data is provided to the
transistor switching circuit. When we applied 0 at the base terminal at that
time the transistor will work as a switch.
It means the collector voltage is
applied is directly available to the emitter pin and through that it reach at
the row pins of the 5x7 Led Dot Matrix Module. The working of the transistor as
a switch is shown in Fig.12c
Fig.12c
Also the connection diagram of 5x7 Led Dot
Matrix Modules to the Micro-controller through the transistor is as shown in
Fig.12c
In the 5x7 Led Dot Matrix Modules, one
led dot consumes 10ma current. Therefore the whole segment having 350(35x10ma)
current is required. There is a problem now because the micro-controller is not
provided that much current therefore do not interface to the 5x7 Led Dot Matrix
Module directly.
Fig.12d
Thus we used one Line driver which
driven the 5x7 Led Dot Matrix Modules’ columns. Here we used 74HC541 octal
buffer/line Driver which is connected to the micro-controller’s Port0 and 5x7
Led Dot Matrix Modules’ columns which are shown in Fig.12d.
The c language program of display one character in the 5x7 Led Dot Matrix Modules is write below;
Program of display only one character in the 5x7 Led Dot Matrix Segment
#include
Void delay_ms ( int
time );
Void main (void)
{
P1=0xFF;
P2=0xFF;
While
(1)
{
P1=0x01;
P2=0x01;
delay_ms (1);
P1=0x02;
P2=0xEE;
delay_ms (1);
P1=0x04;
P2=0xEE;
delay_ms (1);
P1=0x08;
P2=0xEE;
delay_ms (1);
P1=0x10;
P2=0x01;
delay_ms
(1);
}
}
Void delay_ms ( int
time )
{
int
i , j;
for
( i=0; i
for ( j=0; j<1275 font="" j="">
}
Also visit below Post;
Post-10 Create A Character With Row Scanning Method In The LED Dot Matrix Display
Post-11 Create A Character With Column Scanning Method In The LED Dot Matrix Display
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