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Topic: 70 leds one at a time (Read 955 times) previous topic - next topic

amjlopez

Hello:

I need to control 70 leds. One at a time.
Can you help me? what materials do I need for this?
thank you very much.

johnwasser

5 x "4 TO 16 LINE DECODER/DEMULTIPLEXERr" like the 74154 (80 pins)
1 x "3 TO 8 LINE DECODER" like the 74138 (to enable one of the 5 16-bit decoders)

7 data pins to address the two levels of selector.

If you hook a PWM line to one of the gate inputs on the 74154's you can fade each LED in and out.
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CrossRoads

Or an 8x8 matrix driver chip and an 8-bit shift register for the last few LEDs.
Or a 5x7 matrix driver chip like the MAX6953, can do 4 x 35 LEDs.
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.

amjlopez

Thank you very much.

Have you or know any good tutorial to do this?.


mowcius

or 2x M5451 chips - can drive 35 LEDs each.

The CC-Shield uses two of them so you could use the code from that as a starting point:
http://effluviaofascatteredmind.blogspot.com/2009/02/my-first-arduino-shield-arrived.html

CrossRoads

If you go to www.arduino.cc, select Learning, search for 8x8 matrix, you will find some links.

This is one of them
http://www.arduino.cc/playground/Main/DirectDriveLEDMatrix
To me there should be current limiting resistors in there somewhere.
Instead of arduino pins, you could drive with shift registers, etc. as discussed above.
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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