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Topic: 3x MAXIM 7219 in Paralell to drive 5050 SMD LEDs (Read 3450 times) previous topic - next topic

mzure

Hello Guys and Girls!

I want to start my first real arduino project.
I havnt chosen the easiest for my knowledge level but I think with a little of your help it should be possible ;-)

Well by idea is a 3D Pov display (rotating). Mainly there are two LED Matrix (8x8) on both sides of the PCB, and the whole board will rotate so that there is on all 360° the leds visible to create a real 3D image.

But to create a good effect even during not completely dark room I think only 5050 smd leds will have enough power to let it look clearer.
5050 smds have 3 led chips inside each with a total current of 60mA. The 9219 can handle max. 40 mA or so I read somewhere.

My main concern is, if it is possible to stick 3 of the 7219 in parralell to control each one led chip in the 5050.
But they must be perfectly in sync to create no flickering during multiplexing if there is any interference - right?

I hope you can tell my what the best solution is.
My first goal is a working setup showing a still standing image
- I will use a Atmega328P popped out from an UNO to program.
I will post some quick drawings for my idea later

bg mx

CrossRoads

You can find ultrabright LEDs that are blinding at just 20mA/LED.
http://www.superbrightleds.com/moreinfo/component-leds/5mm-rgb-clear-tricolor-led-wide-angle/976/

The 7219's multiplex at 800 Hz, they are addressed using SPI. So you will have to do 3 SPI.transfer commands to update the byte that controls 8 LEDs.
With only 24 bytes needed to update all the display registers on all 3 chips you should be okay.

There is discusion on another thread of 1024 WS2801 chips, controlling an RGB LED each, to make a 32x32 PWM'd RGB LED matrix.
Maybe 64 of those wired up a long string would be better.
You would write out a stream of 3x64 bytes, 500uS after the last byte is sent, the entire display would update at once.
http://www.adafruit.com/datasheets/WS2801.pdf
Someone mentioned 15 cents each from  China supplier.
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

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