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Topic: 16 segment LED with 74LS154 (Read 2 times) previous topic - next topic

microguy

I have 12 of 16 segments LEDs. I would like to use all of them. Can we use 74ls154 (4 line to 16 decoder) with 16 segments LED. Each segments will have thier own transistor. Will that work?

Reid

johnwasser

You have 192 segments.  If you use two of the 74ls154 decoders (one for digits, one for segments) you will only be able to light one segment at a time.  That means each LED is lit only 0.52% of the time, max.  You also have to do updates at 11,520 segments per second to get a 60 Hz update rate.

You would probably be better off using a 16-bit shift register for segments and the 74ls154 only for the digit drive.  Then you can have each digit lit 1/12th of the time (8.3%) and only 720 digits per second to get 60 Hz refresh rate.
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microguy

John,

Thank you for let me know. I am learning. Should we use different chip for it? What about 74HC164 shift register? Can we use other chips which are easier? I was google and try MAX 6954. I am not sure about it?  I was hope someone can give me a simple way to use 12 of 16 segments LEDs. I am open for any suggestions.

Reid

johnwasser

I'm not very experienced with LED matrix design.  The "playground" area of the Arduino site has lots of examples of how to control an array of LEDs.
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