Embedded Interface 7 Segment Display
A 7-segment display is a common electronic display device used to show decimal numbers and some limited characters. It is widely used in embedded systems, digital clocks, electronic meters, calculators, and counters. A 7-segment display is simple, low-cost, and effective for displaying numeric data in embedded projects.
Type of 7 Seg Display
- One 7-Segment Display
- Display Character
- Display Decimal
- Multi 7 Segment Display
- Display Character
- Display Decimal
Structure:
A 7-segment display consists of seven LEDs arranged in an ‘8’ pattern, labeled a, b, c, d, e, f, g, and sometimes an additional decimal point (DP). By turning specific segments on or off, numbers 0–9 and some letters can be displayed.
There are two main types:
- Common Cathode (CC) – All the cathodes of the LEDs are connected together to ground. Each segment in Display is turned on when a HIGH voltage is applied to the respective segment pin.
- Common Anode (CA) – All the anodes are connected together to VCC. Each segment is turned on when a LOW voltage is applied to the segment pin.
Embedded Interface:
Interfacing a 7-segment display with a microcontroller (MCU) involves connecting the segment pins to digital output pins of the MCU.
MCU sets the appropriate pins HIGH or LOW depending on whether the display is common anode or cathode to display a digit.
For example:
- Digit 0 → segments a, b, c, d, e, f ON, g OFF
- Digit 1 → segments b, c ON, others OFF
Driving Techniques:
- Direct Driving: Each segment is connected to a separate MCU pin. Suitable for single digits but requires many pins for multiple digits.
- Multiplexing:
- Used for multi-digit displays to reduce pin usage.
- Digits are turned on sequentially at high speed
- Giving the illusion that all digits are lit simultaneously.
- Driver ICs: ICs like MAX7219 or 74HC595 are often used to drive multiple digits easily with serial communication, reducing MCU pin requirements.
Applications:
- Digital clocks, timers, counters, voltmeters
- Embedded display for sensors and meters
- Scoreboards and panel displays
- Traffic Lights
