Advice on adding x4 4 digit 7 seg desplays to Arduino

Hi all
As the title says I'm seeking advice or a push in the right direction when adding x4 4 digit 7 segment displays to the Arduino.

I'm looking in to a project that from 4 IR. sensors will show a count on x4 4 didgit displays but I'm not knowledgable to know the correct path to go down.

My questios are- can I run my desplays from one board? Do I need drivers for the desplays to work? What board is best suited to this project?.

As I say there's 4 IR. sensors that are there to count objects passing them and each sensor count will display to 4 displays as the counts from each will be in then 1000's.

I could do with viewing a tutorial showing what I need but my searches have mainly brought up outputting to a single desplay.

Thanks in advance.

You need to use MAX7219 drivers for the displays.

Complete displays readily available on eBay.

Paul__B:
You need to use MAX7219 drivers for the displays.

Complete displays readily available on eBay.

Thanks for that I’ve found some good tutorials on this now.
One question- all tutorials although show how to drive multiple 7seg desplays only show coming from one output on the arduino board. Can I have 4 drivers coming from 4 outputs from the boards giving independent desplays?

Cheers

I suppose that you could drive each MAX7219 on a separate bus.
It is like building a separate one lane private highway from every house to every town.

Instead, we use public highways and simply turn off one road to another public road in order to get to our destination.

You can place all the 7219s in a daisy chain. You can still address each digit independently. e.g. show 5 on digit 14 and 3 on digit 2

In fact your 16 digits can be controlled by two 7219s. Or by four controllers if you want. At a cost of 3 GPIO pins. If you add it to an existing SPI bus, it only needs one GPIO as chip select.

David.

Kudos to David! That was a superb analogy.

Markiep:
all tutorials although show how to drive multiple 7seg displays only show coming from one output on the Arduino board.

Because that is the most sensible way of doing it.

Markiep:
Can I have 4 drivers coming from 4 outputs from the boards giving independent displays?

The displays will always be independent.

OK, perhaps you are thinking that it will be easier to change one display value at a time. You are thinking in mechanical terms instead of digital logic terms.

Let's think this through. While you could have the four numbers in separate variables and write display code that you feed by reading that variable and feeding that along with a pointer to the particular display "select" line, to the display code, it is generally much cleaner to store the values in an array and use display code that successively indexes the array to send them all to the display chain.

Keep in mind, we are using MAX7219s - you only need to do this when you change the values; it is extremely fast anyway and the MAX7219 is doing the multiplexing for you.

Hi guys and thanks.

Some good analogies there thanks. Where I was going wrong is- as I will have 4 separate IR. sensors counting 4 separate items and 4 separate 7seg desplays (4x4) showing the counts I assumed the desplays had to go on in own output.

To be clear as I'm using 4x4 desplays (16) I only require 2 7219's and these on one output and let the code do the work ?

I suppose the proof will be in experimenting and I'll order what's required and give it a go. This is my first time in Arduino so wanted to ask my thoughts.

There's one thought I could do with in a push in the right direction. Another option I've been mulling over is rather than have the results shown via 7seg desplay I like the thought of sending the results to a readout on the PC. But not the simply serial readout but big bold digital looking text. The readout would show the results from all four IR. sensors.

Any advice please