The 7 segment display is found in many displays such as microwaves or
fancy toaster ovens and occasionally in non cooking devices. It is just
7 LEDs that have been combined into one case to make a convenient
device for displaying numbers and some letters. The display is shown on
the left. The pin out of the display is on the right.
This version is a common anode version. That means that the positive
leg of each LED is connected to a common point which is pin 3 in this
case. Each LED has a negative leg that is connected to one of the pins
of the device. To make it work you need to connect pin 3 to 5 volts.
Then to make each segment light up, connect the ground pin for that led
to ground. A resistor is required to limit the current. Rather than
using a resistor from each LED to ground, you can just use one resistor
from Vcc to pin 3 to limit the current.
The following table shows how to form the numbers 0 to 9 and the letters
A, b, C, d, E, and F. '0' means that pin is connected to ground. '1'
means that pin is connected to Vcc.
To Display
a (Pin 1)
b (Pin 10)
c (Pin 8)
d (Pin 6)
e (Pin 5)
f (Pin 2)
g (Pin 9)
0
0
0
0
0
0
0
1
1
1
0
0
1
1
1
1
2
0
0
1
0
0
1
0
3
0
0
0
0
1
1
0
4
1
0
0
1
1
0
0
5
0
1
0
0
1
0
0
6
0
1
0
0
0
0
0
7
0
0
0
1
1
1
1
8
0
0
0
0
0
0
0
9
0
0
0
1
1
0
0
A
0
0
0
1
0
0
0
b
1
1
0
0
0
0
0
C
0
1
1
0
0
0
1
d
1
0
0
0
0
1
0
E
0
1
1
0
0
0
0
F
0
1
1
1
0
0
0
Now, we want to run the display with the AT89C51 microcontroller. We
will use Port 0 to run the display. Connect the AT89C51 to the 7
segment display as follows.
Program to display "0" on the seven segment display
; PROG2 - Second Program, Display 0 on seven segment display
;
ORG 0000H ; Execution starts here
SETB P0.3 ; Turn off the g segment
CLR P0.1 ; Turn on the a segment
CLR P0.0 ; Turn on the b segment
CLR P0.6 ; Turn on the c segment
CLR P0.5 ; Turn on the d segment
CLR P0.4 ; Turn on the e segment
CLR P0.2 ; Turn on the f segment
.jpg)
The 7 segment display is found in many displays such as microwaves or
fancy toaster ovens and occasionally in non cooking devices. It is just
7 LEDs that have been combined into one case to make a convenient
device for displaying numbers and some letters. The display is shown on
the left. The pin out of the display is on the right.
This version is a common anode version. That means that the positive
leg of each LED is connected to a common point which is pin 3 in this
case. Each LED has a negative leg that is connected to one of the pins
of the device. To make it work you need to connect pin 3 to 5 volts.
Then to make each segment light up, connect the ground pin for that led
to ground. A resistor is required to limit the current. Rather than
using a resistor from each LED to ground, you can just use one resistor
from Vcc to pin 3 to limit the current.
The following table shows how to form the numbers 0 to 9 and the letters
A, b, C, d, E, and F. '0' means that pin is connected to ground. '1'
means that pin is connected to Vcc.
To Display
|
a (Pin 1)
|
b (Pin 10)
|
c (Pin 8)
|
d (Pin 6)
|
e (Pin 5)
|
f (Pin 2)
|
g (Pin 9)
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
1
|
1
|
1
|
0
|
0
|
1
|
1
|
1
|
1
|
2
|
0
|
0
|
1
|
0
|
0
|
1
|
0
|
3
|
0
|
0
|
0
|
0
|
1
|
1
|
0
|
4
|
1
|
0
|
0
|
1
|
1
|
0
|
0
|
5
|
0
|
1
|
0
|
0
|
1
|
0
|
0
|
6
|
0
|
1
|
0
|
0
|
0
|
0
|
0
|
7
|
0
|
0
|
0
|
1
|
1
|
1
|
1
|
8
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
9
|
0
|
0
|
0
|
1
|
1
|
0
|
0
|
A
|
0
|
0
|
0
|
1
|
0
|
0
|
0
|
b
|
1
|
1
|
0
|
0
|
0
|
0
|
0
|
C
|
0
|
1
|
1
|
0
|
0
|
0
|
1
|
d
|
1
|
0
|
0
|
0
|
0
|
1
|
0
|
E
|
0
|
1
|
1
|
0
|
0
|
0
|
0
|
F
|
0
|
1
|
1
|
1
|
0
|
0
|
0
|
Now, we want to run the display with the AT89C51 microcontroller. We
will use Port 0 to run the display. Connect the AT89C51 to the 7
segment display as follows.
Program to display "0" on the seven segment display
; PROG2 - Second Program, Display 0 on seven segment display
;
ORG 0000H ; Execution starts here
SETB P0.3 ; Turn off the g segment
CLR P0.1 ; Turn on the a segment
CLR P0.0 ; Turn on the b segment
CLR P0.6 ; Turn on the c segment
CLR P0.5 ; Turn on the d segment
CLR P0.4 ; Turn on the e segment
CLR P0.2 ; Turn on the f segment
.jpg)
