A Guide for Interfacing Seven Segment Displays with Arduino
Visual indication has become essential in modern electronic devices for enhancing user interaction. One such long standing solution is the Seven-Segment Display. Used widely across industries for decades, these displays excel in showcasing numeric values. From instruments to space shuttles, they offer a practical, cost-effective, and highly readable way to display numbers. Unlike LCDs, they maintain readability in various lighting conditions, making them ideal for applications such as counters and token systems.
Seven Segment Display:
The Seven Segment Display is showcased in a simulation where an Arduino counts from 0 to 9 and repeats, displaying the values on the display. These displays come in various sizes, ranging from 0.28 inches to 18 inches, with the most common size being 0.56 inches.
These displays consist of seven LEDs arranged to form the digit eight, with an additional LED for indicating the decimal point. The LEDs are wired to form a common pin, while each LED represents a specific segment of the digit. By controlling the appropriate pins, we can generate character patterns to display numbers from 0 to 9.
Types of seven segment display:
Seven Segment Displays are divided into two types: Common Cathode (CC) and Common Anode (CA). The classification is based on how the LED pins are connected to the common pin.
Common Cathode Displays:
In CC displays, all the cathodes of the LEDs are linked to the common pin, which is then connected to the ground rail. Activating individual LEDs is done by applying a high pulse or logic 1 signal.
Common Anode Displays:
In CA displays, all the anodes of the LEDs are connected to the common pin, which is then linked to the positive rail. Activation occurs by applying a low pulse or logic 0 signal.
Each type has a different method of operation but achieves the same result: illuminating specific segments to display numbers or characters.
Displaying Number:
To display numbers or patterns on a Seven Segment Display, the corresponding pins must be activated with the appropriate signal. For Common Cathode displays, a Logic 0 or LOW signal is used, while for Common Anode displays, a Logic 1 or HIGH signal is applied. This allows for the display of digits from 0 to 9. Additionally, alphabets can also be displayed using these displays.
A truth table is provided for both Common Cathode and Common Anode displays, outlining the activation signals for each segment to display the desired numbers or alphabets.
A Tinkercad simulation is available for interfacing the Seven Segment Display with an Arduino. The simulation demonstrates the display of numbers 0 to 9 on the display. Users can modify the provided code as needed by accessing the code button in the simulation interface.
Connecting a Seven Segment Display with an Arduino:
Circuit Connection:
Place the display module on a breadboard with the decimal point facing downwards.
Connect either common pin (pin 3 or pin 8) of the display to the ground.
Wire the remaining pins to digital pins D2 to D9 of the Arduino through current limiting resistors. The value of these resistors, such as 330 ohms, should be chosen based on display color and size to ensure around 10mA current for the LEDs.
Circuit Diagram:
Refer to the provided connection diagram for visual guidance on how to wire up the display module with the Arduino.
Install the SevSeg library via the Arduino IDE’s Library Manager.
Create a new sketch and copy the provided Arduino example code into it.
This code counts from 0 to 9 and resets back to 0, displaying the numbers on the Seven Segment Display. Adjustments to the code can be made as needed.
Explanation:
The SevSeg library is utilized in the sketch to control the display.
Variables such as numDigits, digitPins, and segmentPins are defined to set up the display.
The setup() function initializes the SevSeg library with specified parameters, such as display type and brightness.
In the loop() function, a for loop counts from 0 to 9, displaying each number on the display with a 1-second delay between each count.
This process allows for interfacing a Seven Segment Display with an Arduino, enabling the display of numeric values with ease.
Here are some projects featuring Seven Segment Displays:
- Raspberry Pi Interface: Connect Seven Segment Display to Raspberry Pi with guide and code.
- Arduino Clock: Build digital clock using Arduino and four 7-segment displays.
- 555 Timer Counter: Create digital counter with 555 Timer IC.
- ARM7-LPC2148 Interface: Connect Seven Segment Display to ARM7-LPC2148 with circuit diagram and code.
- Object Counter Circuit: Design simple object counter circuit without microcontroller.
Seven segment displays are fundamental tools in electronics, providing a straightforward and dependable method for numeric display tasks. By grasping their various types, operational concepts, and utilization with platforms such as Arduino and Raspberry Pi, enthusiasts can explore practical applications and expand their knowledge in electronics projects.
