7-Segment Display

Seven segment LED display with configurable digits and colors

Seven segment LED display

Pin names

A · pin

Top segment

B · pin

Top-right segment

C · pin

Bottom-right segment

D · pin

Bottom segment

E · pin

Bottom-left segment

F · pin

Top-left segment

G · pin

Middle segment

DP · pin

Dot LED

COM · pin

Common pin (for single digit displays)

DIG1 · pin

Digit 1 pin (for multi-digit displays)

DIG2 · pin

Digit 2 pin (for multi-digit displays)

DIG3 · pin

Digit 3 pin (for multi-digit displays)

DIG4 · pin

Digit 4 pin (for multi-digit displays)

CLN · pin

Colon pin (optional, for clock mode)

COM is the common pin for a single digit 7-segment display. For multi digit displays, use DIG1…DIG4.

With the default common attribute setting of anode, the segment pins (A…G, DP, CLN) are connected to the cathode (negative side) of the LEDS, and the common pins (COM, DIG1…DIG4) are connected to the anode (positive side) of the LEDs. Segments are lit by driving their pins low. Setting common to cathode reverses this behavior, with the segment pins turning on when high.

Attributes

common · string · default: "anode"

The common pin configuration: “cathode” or “anode”

digits · string · default: "1"

Number of digits: “1”, “2”, “3” or “4”

colon · string · default: ""

Set to “1” to show the colon (clock mode)

color · string · default: "red"

The color of the segment LEDs

Using the 7-segment display

For a single digit, you’ll need 8 microcontroller GPIO pins. Each pin should be connected to a single segment through a resistor, and the common pin should be connected to 5V (or GND if you are using the common cathode variant). You can spare one pin (DP) if you don’t use the dot LED. Turn a segment on by driving the corresponding segment on (or HIGH for the common cathode variant).

For multiple digits, you’ll need 8 microcontroller pins for the segments and the dot plus one extra microcontroller pin for each digit. So if you have 4 digits, you’ll need 12 microcontroller pins in total. Controlling the display in this mode is a bit tricky, as you’ll need to continuously alternate between the different digits.

Luckily, there are libraries that can help:

• On Arduino: Use the SevSeg library.
• On the Raspberry Pi Pico: The PIO peripheral can take care of refreshing the display for you. See the examples below.

If you are out of microcontroller pins, consider using a 74HC595 Shift Register to drive the display.

Simulator examples

• SevSeg example: Counter
• SevSeg example: String with period
• Arduino alarm clock
• Static versus multiplexed signals for 7-segment displays
• ATtiny85 7-segment clock
• ATtiny85 8 digit counter
• 7-segment on the Raspberry Pi Pico (using PIO)
• 7-segment on the Raspberry Pi Pico (MicroPython)