single color addressable led

Hi, I want to build huge 7segment display. I already made one using LED strips, but I was switching them using transistors, so I had to use on pin for each segment and I had problems with overheating ATmega when switching many transistors, so I wanted to build it using addressable LED strip. But I can't find single color one. I need maximum brightness, so I'd like to use SMD5050, all 3 LEDs on maximum, but all addressable strips are RGB, so this give me white color, but I'd like to have red one.

So, is there any way to have single color adressable led strip, or does exist something like addressable transistor? Or some kind of addressable switch, that I will be able to connect LED to every one and then switch every on/off using one or two pins like addressable LED strips. Thanks

"so I had to use on pin for each segment and I had problems with overheating ATmega when switching many transistors" Maybe not your desired answer, but since you brought it up: Did you have a resistor between the arduino pin and the transistor base? What value resistor? With a proper resistor, the arduino should not overheat.

Maybe something like the MAX7219 decoder for 7 segment led may be interesting

http://playground.arduino.cc/Main/MAX72XXHardware

How many digits do you plan to have?

parmanik: I want to build huge 7segment display. I already made one using LED strips, but I was switching them using transistors, so I had to use on pin for each segment and I had problems with overheating ATmega when switching many transistors, so I wanted to build it using addressable LED strip.

Simply because you got the wiring wrong is no a reason to swap to another approach.

Clearly you should continue to use the LEDs strips you already have that give the brightness you want and drive them properly.

I presume you want to use 12V strips. TPIC6B695s would be worth looking into for a start, very easy to drive from a Pro Mini.

Even if I solved overheating, I still have problems with pins. I want use ATmega328p, so I have only 14 pins. Till now it was OK, I was using analog as inputs and driving two digits with one chip. But now, I need 4 digits, so I can't use tranzistors. I need something adressable.

I have looked at lots of LED strips and have only seen RGB APA strips. None that are one color are APA.

Look at MAX72xx (MAX7219 or MAX7222) for a help with your pin shortage. I easily drive 8 8x8 LED matrices with just 3 pins. Each matrix has a MAX7219 behind it. So that is 8x8x8 or 512 LEDs with 3 pins.

Look at the LedControl library to talk to the MAX72xx chip.

Mike

Max7219/7221 cannot work with 12V (unless many extra transistors or chips are added).

You should go with Paul__B's suggestion of tpic6x595 chips, one per digit. If you daisy-chain the chips, only 3 Arduino pins will be needed.