Custom LED matrix

Hello,

I have bought a 10cm x 15cm proto board and I want to make a LED matrix for showing messages using Arduino MEGA 2560 R3. Where should I start from? What will I need? I am going to use battery.

Thanks....

I would start by putting your parts in the corner shelf and purchasing the Arduino Cookbook and then read it. You should also go on line and go through the many tutorials and videos available to you. Many of the good tutorials are available on this web site. By this time you should be able to figure out what you need, and I will be surprised if you use a battery unless it is a large one. You might consider a LCD type of display. This response is to help you get started in solving your problem, not solve it for you.
Good Luck & Have Fun!
Gil

How many LEDS?

What kind of LEDS?

Is there a reason to build your own matrix LED set-up? Instead of just buying one the correct size?

Perhaps a simple MAX72xx type chip will help for this project.

I consider learning the MAX7219 chips a beginner tutorials/project

The more LEDs I can fit on a 10 x 15 cm proto board.
Yes, pink 5mm. 3 - 3,2 Volts
I want specific size and wavelength for what I want to achieve.

.....................and the count?

1 MAX chip can control up to 64 leds...

Do I need to put a resistor to each LED? Or is it better to put a resistor to every array of LEDs?

A matrix-wired led display can't have most of the leds ON at any instant. You might do a whole row but that's it.
You can have 2 maybe 3 leds appear to be bright or several appear to be on or many appear to be dim... as long as the place you look isn't brightly lit but that's it.
Matrix wiring has limited brightness since the lit leds have to share on-time.

You won't have that problem using led drivers or WS2811/12 leds whether in strip or string form. Using led strip should save a LOT of handwork over soldering individual leds and resistors.

Your choice.

alex5678:
The more LEDs I can fit on a 10 x 15 cm proto board.
Yes, pink 5mm. 3 - 3,2 Volts
I want specific size and wavelength for what I want to achieve.

100x150 mm can fit 20x30 = 600 5mm LEDs.

That's going to be 10 MAX7219 chips - and a LOT of soldering. I'd design a simple PCB for this... then at least you can get the connections right quite easily :slight_smile:

Supposing there are cases I want to light on all the LEDs for 1 sec - 2sec. What is the best way to do it? What battery should I use?

alex5678:
Supposing there are cases I want to light on all the LEDs for 1 sec - 2sec. What is the best way to do it?

Depends on how they're controlled. You did not specify that part yet.

What battery should I use?

A battery that can deliver sufficient current at a suitable voltage. This depends on how they're wired, controlled, and how bright the LEDs have to be. All of which you have not specified yet.

wvmarle:
Depends on how they're controlled. You did not specify that part yet.

That do you suggest?

wvmarle:
A battery that can deliver sufficient current at a suitable voltage. This depends on how they're wired, controlled, and how bright the LEDs have to be. All of which you have not specified yet.

They demand 20mA, 3,0-3,2 Volt

Google “charlieplexing”

alex5678:
That do you suggest?

See #7.

They demand 20mA, 3,0-3,2 Volt

That 20 mA is probably their maximum rating, typical for LEDs. But well, it's enough to do the math. 20 mA x 600 LEDs = 12A of current for them to be all lit at maximum brightness. The MAX7219 needs 5V, so a stack of power banks will do fine (they can typically deliver 2-3A each, with 10x MAX7219 that'd be 5 power banks, one for each two MAX7219).

alex5678:
Supposing there are cases I want to light on all the LEDs for 1 sec - 2sec. What is the best way to do it? What battery should I use?

Don't use matrix wiring then. That is where you wire 1 pin per row and 1 pin per column (with a diode at each crossing as well as a led and resistor) to save pins ---- matrix wiring is at the pin level.

You can light a few leds on that wired matrix by shining each a few ms in turn while the others are off. Your eyes will see them all as lit but not 100% bright. Close up, full bright leds hurt my eyes -- I'm used to dimming leds by blinking them faster than eyes can see.

If you get the driver chips like the MAX7219 then the leds wire to the chips and you can shine all the leds any time.

Batteries? At 20 to 25mA per single color led, you will want batteries with a LOT of milliamp hours of charge. A car battery with a buck converter could run 600 of those leds for a good while though.

You state that you want them all on some of the time.
What else do you want to display?

You can use MAX72xx chips, or column-row multiplexing for individual LED control... or simple rows and columns if you’re not displaying a matrix symbol set, but just blobs of light.
Single colour or RGB(W) combinations?

Over to you.

Pink LED 5mm, 3,0 - 3,2 Volts, 20 mA.

That’s the only question I didn’t ask !
At this stage it’s irrelevant

All ON at the same time requires 1 pin per led (driver pins count) and the required power.

The leds you have may be rated for 20mA max but check how much you really give may be more like 12mA between what resistor you use and how bright You want after testing.

lastchancename:
That’s the only question I didn’t ask !
At this stage it’s irrelevant

lastchancename:
Single colour or RGB(W) combinations?

Single color! Pink LED...

Maybe I have confused you...So the concept is a led matrix to write messages, but when it needs to light on all the LEDs instantly for 1-2 sec, and then continue to work as a LED messages matrix.