I would like to drive a 16 levels bargraph from 4 arduino's outputs and I need a BCD decoder to drive the leds.
Do you know of a decoder that would do the trick? The usual decoders/multiplexers (74154, ...) are not suitable since they only activate one output at a time. The goal here is to successively light several LEDs at a time.
Thanks for your help.
Bernard
BCD means ten different values in the 4 bit nibble, 0 to 9.
So there will be no BCD decoder driving a 16 level bar graph.
I suppose something like this: http://www.slsemicon.co.kr/data_down/sl74hc/HC154.PDF but you may have to invert those diodes. But it fails this test: The goal here is to successively light several LEDs at a time unless you multiplex it rapidly.
sorry you are right... forget about BCD, just decoder.
You are describing a shift register, like 74HC595. By the way, you really need current limiting resistors on the LEDs.
Actually, you described an "addressable latch" but I don't think you will find that as easy to find or work with.
A led driver chip may also suit here. If the bar display is common cathode, as illustrated, an HT16K33 should work and you could even drive 8 of those bar displays with one chip. This does not require current limiting resistors and can be addressed via I2C.
It's probably overkill but, a MAX7219 would also work and there'd be the capability to drive an additional forty-eight LEDs if needed.
Hello bernard_paris
Check this:
TPIC6B595, like an HC595 with higher drive capability built in or CD54HC259 addressable latch as @anon57585045 suggested.
edit: Sorry, not a reply to @dougp specifically.
@EmilyJane Cool, thanks for this, I will use 74HC595.
See:
Example with a tpic6b595 driving leds
Is the bar graph a component, or custom made? If it's a component, please link to the specifications.
Not, unfortunately with common cathode displays which the OP appears to have illustrated in the first post. The TPIC6B595 can sink only.
Ah, I overlooked that. Good point.
No problem. I make mistakes too. Although, having said that, I can't think of a specific example offhand 
lol. OP didn't post what specific bar graph they were using so those individual LEDs could be hooked up any which way. 
The forum guidelines strongly suggest posting specific vs. general information. I'm asking for a data sheet or reference for the part.
This forum has a mixture of experienced and inexperienced experimenters. We can't just assume normal diligence in such cases.
Oh yes a shift register, a good idea, I didn't thought about it. Common cathod is not a constraint for me I can change my mind for that.
Thank you, Bernard.
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