7 Segment Display
If your Arduino application only needs to display numbers, consider using a seven-segment display. The seven-segment display has seven LEDs arranged in the shape of number eight. They are easy to use and cost effective. The picture below shows a typical seven-segment display.
Seven segment displays are of two types: common anode and common cathode. The Internal structure of both types is nearly the same. The difference is the polarity of the LEDs and common terminal. In a common cathode seven-segment display (the one we used in the experiments), all seven LEDs plus a dot LED have the cathodes connected to pins 3 and pin 8. To use this display, we need to connect GROUND to pin 3 and pin 8 and, and connect +5V to the other pins to make the individual segments light up. The following diagram shows the internal structure of common-cathode seven-segment display:
anode display is the exact opposite. In a common-anode display, the positive terminal of all the eight LEDs are connected together and then connected to pin 3 and pin 8. To turn on an individual segment, you ground one of the pins. The following diagram shows the internal structure of the common-anode seven-segment display.
The seven segment are labelled a-g, with the dot being “dp,” as shown in the figure below:
To display a particular number, you turn on the individual segments as shown in the table below:
|
Digit gfedcba |
abcdefg |
a |
b |
c |
d |
e |
f |
g |
|
|
0 0×3F |
0×7E |
on |
on |
on |
on |
on |
on |
off |
|
|
1 0×06 |
0×30 |
off |
on |
on |
off |
off |
off |
off |
|
|
2 0×5B |
0×6D |
on |
on |
off |
on |
on |
off |
on |
|
|
3 0×4F |
0×79 |
on |
on |
on |
on |
off |
off |
on |
|
|
4 0×66 |
0×33 |
off |
on |
on |
off |
off |
on |
on |
|
|
5 0×6D |
0×5B |
on |
off |
on |
on |
off |
on |
on |
|
|
6 0×7D |
0×5F |
on |
off |
on |
on |
on |
on |
on |
|
|
7 0×07 |
0×70 |
on |
on |
on |
off |
off |
off |
off |
|
|
8 0×7F |
0×7F |
on |
on |
on |
on |
on |
on |
on |
|
|
9 0×6F |
0×7B |
on |
on |
on |
on |
off |
on |
on |
|
|
A 0×77 |
0×77 |
on |
on |
on |
off |
on |
on |
on |
|
|
B 0×7C |
0×1F |
off |
off |
on |
on |
on |
on |
on |
|
|
C 0×39 |
0×4E |
on |
off |
off |
on |
on |
on |
off |
|
|
D 0×5E |
0×3D |
off |
on |
on |
on |
on |
off |
on |
|
|
E 0×79 |
0×4F |
on |
off |
off |
on |
on |
on |
on |
|
|
F 0×71 |
0×47 |
on |
off |
off |
off |
on |
on |
on |
Interfacing with Arduino
The pins of seven-segment display are connected to Arduino pins 2-9, as shown in the table below. Common pins (pin 3 and pin 8) are connected to GND and dp is left unconnected, because it is not used in this experiment
|
Seven segment pins |
Arduino pins |
Wire Color |
|
1(e) |
6 |
orange |
|
2(d) |
5 |
white |
|
3,8(COM) |
GND |
n/a |
|
c |
4 |
yellow |
|
5(dp) |
– |
|
|
6(b) |
3 |
red |
|
7(a) |
2 |
blue |
|
9(f) |
7 |
cyan |
|
10(g) |
8 |
green |
Code
void setup()
{
// define pin modes
pinMode(2,OUTPUT);
pinMode(3,OUTPUT);
pinMode(4,OUTPUT);
pinMode(5,OUTPUT);
pinMode(6,OUTPUT);
pinMode(7,OUTPUT);
pinMode(8,OUTPUT);
}
void loop()
{
// loop to turn leds od seven seg ON
for(int i=2;i<9;i++)
{
digitalWrite(i,HIGH);
delay(600);
}
// loop to turn leds od seven seg OFF
for(int i=2;i<9;i++)
{
digitalWrite(i,LOW);
delay(600);
}
delay(1000);
}
Applications of Seven Segment Displays
- The applications of seven segments are mostly in digital calculators, electronic meters, digital clocks, odometers, digital clocks, clock radios, etc.
- Today most of the 7 segment applications are using LCDs, because of low current consumption.
Reference:
https://www.allaboutcircuits.com/projects/interface-a-seven-segment-display-to-an-arduino/
https://circuitdigest.com/microcontroller-projects/7-segment-display-interfacing-with-arduino
https://create.arduino.cc/projecthub/SAnwandter1/programming-4-digit-7-segment-led-display-2d33f8
https://www.circuitbasics.com/arduino-7-segment-display-tutorial/