max7219

This is with only 5v and ground.why are they all lit the same? 3 are from my kit,5 I soldered. I can't get any examples to work with any of them. Mostly I get random leds lit and/or moving. Are the chips programmed by sketches?

Hello and welcome.

First of all, give yourself a firm slap across the face man! You are acting hysterically and not making much sense. Calm down, take a sip of brandy and start from the beginning.

Are you trying to power 8 modules with USB power? That won't work. You need an external power supply.

Try testing each module in isolation.

The chips have to be programmed by an Ardino sketch, yes, but there will probably be a "default" pattern which is displayed if no data is sent by the Arduino.

Its possible you have purchased the "faulty" kits from eBay, where the wrong type of matrix has been supplied.

Paul

As mentioned, you need an external power supply and a sketch for control.

It appears you have plugged into 3.3v from your image.
.

Not enough is wired up. Each chip needs +5, Gnd, and Clock, Data, Chip Select (I use SPI to supply those myself, many libraries don't). +5, Gnd, Clock, Chip Select will all be in parallel to each chip, data is daisy chained from device to device (Or, data can be in parallel to all, and unique chip select from uC needs to go each device).
MAX7219 has 5 control registers and 8 shift registers for data. If you don't set up the control register and load in some good data, then all bets are off as to what is displayed.

With so many displays, you should look into the parola.h library for Arduino.
https://parola.codeplex.com/

I know it sounds self-promoting but I'm about to upload a YouTube video showing exactly how these need to be programmed to get a moving message across one or more matrix displays.

On this occasion I will not say it's easier than you think either. In fact, it's quite tricky but eminently possible. However, most people will end up using a library which I discuss at the end of the video. My video concentrates on HOW it all works and WHY. It starts with getting a moving sprite (or pattern) on just one matrix then expands that to multiple LED matrices. If you're not using a library which does all this hard work for you then this is not for absolute beginners!

For a start you need to understand that each column on the LED matrix is individually controlled by a byte pattern. To move them you literally redisplay the entire column's worth of information in a new position. To display any kind of pattern (which includes letters and sprites) you move all the columns to the left (or right etc) one at a time. There is no magic to doing this.

And if you connect multiple LED matrices up together like you have, each matrix will display the SAME information unless you have told it not to!

Perhaps this is the nudge I need to get the video finished and published... Any takers?

Edit: I forgot that the two videos on my YouTube channel (#1 & #2) which were test videos of just a few few seconds each do demonstrate what I mean on a single LED matrix - I had to wait for an eternity for that slow boat from China to deliver further ones before I could continue my video!

And yes, CrossRoads has already mentioned you need all 5 pins connected up with the DataOut of one LED Matrix going to the DataIn of the following (daisy chained).

jeffp60:
This is with only 5v and ground. Why are they all lit the same?

They just might be the modules sold with the wrong displays though they generally light up all LEDs at once without meaningful data connection.

There is something else - the Chip Select line (which if correctly wired, is common to all) requires a 47k pull-up (i.e., to 5V) otherwise you often will have a random display before the chip is initialised. You could try this on one display in your chain to confirm for a start.

Actually found the problem. I rotated the leds 180. They all went out ant works fine.

jeffp60:
I rotated the leds 180.

Well done Jeff. One of those "i could have kicked myself" moments. We are all familliar with those! After several hours of frustration trying to get something to work, its not the best time to post a request for help. Better to sleep on it.

Do bear in mind my recommendation about the pull-up on the chip select.