Weird led display that uses pins as both ground and as power

Other Hardware General Electronics
1

So, I have this strange led display that I scavenged from an old radio.
It has seven pins, each of which acts as both a positive and a ground. For example, whenever I put power on the first pin and ground on the second pin, it lights up the top segment of one of the 7 segment displays.
But then, I need to use the first pin as ground and the second pin as positive (aka, swapped roles) to get a different segment on one of the 7-segs.
My question is: how do I program my arduino uno to switch an output pin to ground, and vice versa? Thanks ahead of time.

2 
digitalWrite(pin, LOW);

Do not attempt to have the pin "sink" or source more than about 20 mA, and be sure use current limiting resistors for the display segments.

3

is that what low does? :smile: Im such a dummy. Ok, thanks!

4

(Ominous music plays) I don't have enough resisters :exploding_head:

5

digitalWrite(pin, LOW) is essentially "ground" and digitalWrite (pin, HIGH) will be about 5V

6

I actually have a new question how do I use four resistors to separately power seven pins

7

You put them together for one night in the dark and next morning you check if they have any babies..

1 Like
8

that's actually crazy Ill try that thanks a bunch

9

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