Pin names
Top segment
Top-right segment
Bottom-right segment
Bottom segment
Bottom-left segment
Top-left segment
Middle segment
Dot LED
Common pin (for single digit displays)
Digit 1 pin (for multi-digit displays)
Digit 2 pin (for multi-digit displays)
Digit 3 pin (for multi-digit displays)
Digit 4 pin (for multi-digit displays)
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.
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
The common pin configuration: “cathode” or “anode”
Number of digits: “1”, “2”, “3” or “4”
Set to “1” to show the colon (clock mode)
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.