Picture of Different methods of driving 7 Segment LED displays with Arduino
7 Seg Push button.JPG
I would just like to show a few different methods of connecting 7 segment LED displays to an Arduino or Atmega 328 IC. They are only simple counter codes either automatically counting via the code or incremented / decremented via a pair of push button switches or a potentiometer . I have used 220 Ω resistors in all these circuits but you would be advised to calculate the correct ones required for the particular 7 segment displays that your are using. This will ensure that you do not damage the IO pins of the 328 IC. The constraints to these maximum currents, courtesy of
are -
- The IO pins have an absolute maximum rating of 40 mA per pin.
- Also the following groups of pins should not have more than 100 mA drawn from them
* Digital pins 0 to 4
* Digital pins 5 to 1
* Analog pins A0 to A5
- In addition to that, the entire processor chip has a maximum rating of 200 mA current consumption.

The 7 segment LED displays are common cathode and the shift register is a 74HC595. I have included a photo of the 7 segment LED from the front showing the relationship between the pin numbers and the corresponding LED segment that the pin controls.

BlueRock1 year ago
Great Instructable Pedro!