Adafruit RGB 7 Segment 1" Multiplexing 3 for Speedo

Hey Guys,
i am new in Arduino. I have basic Knwoledge in programming/scripting (understand fast) and also in elektronic stuff.
But know my Plan:

I want to “read” with a reed-sensor my speed of the wheel. Connected to a arduino nano every (more powerfull than nano). If you have an idea for a diffrent nano tell me. The thing is, i dont have much place, so a nano is my first choice.

So the arduino reads the Speed and displays it to 3x RGB 7 Segment Displays from adafruit. I love how they look and they have the perfekt size for my Speedo. Problem: they have 21 pins. I already found one article in the forum about wiring one of these. So i need help if there is an easy way to wire 3 of them. If someboday have designed a backpack i would definitely know :smiley:

For my Knowledge know: I need 3 74HC595`s to wire one display. Means 9 of them PLUS one to connect the 3 together?? Or isnthere an esier way.

Other option: 3x 5x7 Matrix. But i think thats the same problem.

Here is one wire option i found in the forum for one.
Hope you can help me :slight_smile:

Hi and welcome to the forum.

What is your level of experience in electronics and programming? For example do you know what multiplexing means? You mention multiplexing in the topic subject, but in your post you describe only methods which do not involve multiplexing.

What is your project? Is it for a motorcycle? What are your requirements for using these displays in your project? What and how many colours do you wish to use, do you want to have different colours on different digits of even different segments at the same time? If so, why? Can you not find a 1" single colour display that you like?

These displays are, I think, intended as a novelty item, a toy item, attractive to beginners but not very practical for real projects. They will be much more difficult to use them normal displays. So you must have very good reasons to choose them.