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12 Segment Bar Graph - Weird pinout !

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Sync

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I have this nice looking 12 segment bar graph arrays but i just don't understand the pinout of some of the leds !
See attachment diagram gif, the leds are B, C, E, F, G, H, J and K.
Is there a way to use it ?
 

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I have this nice looking 12 segment bar graph arrays but i just don't understand the pinout of some of the leds !
See attachment diagram gif, the leds are B, C, E, F, G, H, J and K.
Is there a way to use it ?
hi,
These bars can be driven without any problem, the important point is,what device do you want to drive them with, whats the project.:)
 
I use multiple leds in my project already, like 10 or 12 in rows. I can drive the leds with no problem with my hardware. I just want to know why the leds in this 12 segment bar graph are not like the other bar graph available, each led has a pair of pin individually, but not this model.
 
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I use multiple leds in my project already, like 10 or 12 in rows. I can drive the leds with no problem with my hardware. I just want to know why the leds in this 12 segment bar graph are not like the other bar graph available, each led has a pair of pin individually, but not this model.

hi,
I suspect its to limit the number pins on the LED, else it would require 24 pins.
Do you have a model number.?

I could check to see how others are using them.:)
 
The way you drive it depends on what kind of output you expect. "Bar Mode" would be different than "Dot mode". Which chip do you want to drive it with? I'll admit it IS a silly way of saving pins. They could just have made it common Anode or common Cathode or formed a matrix to reduce pin count.
 
Any thoughts

I have this same problem. I can not seem to find a chip suitable to drive these that is still available. The only chips I find are all discontinued. Ive tried using LM3915 (ten segment driver) and while it sort of works it doesnt look right. If anyone can answer this it would be apreciates as I have been banging my head on this problem litterally for over a year.

Oh yeah.. I am trying to drive them in BAR mode.
 
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You're right, that is a weird pinout.

You could drive it with a PIC easily enough. In order to get a consistent brightness, strobe the LEDs that share a pin alternately, and also strobe the unshared-pin LEDs at a 50% duty cycle. So you'd have 2 cycles:

Cycle 1: B,E,G,J are on.
Cycle 2: C,F,H,K are on.

For the individual LEDs, pick a cycle to light those up on. You could light all of them on cycle 1 for example, or put half of them on cycle 1 and half on cycle 2. So, for example:

Cycle 1: A,B,E,G,J,I are on.
Cycle 2: C,D,F,H,K,L are on.

Without strobing, you'd have to use a constant-current source to run the pairs of LEDs in series, or individual LEDs in the case where one needs to be lit and another unlit, to get a consistent brightness. The strobing method is much easier.

You'd think they would have just given all the LEDs a common cathode, or a common anode, thus only needing 13 pins for 12 LEDs. That arrangement is much easier to drive as well.
 
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Strobing might work but that would be WAY too much work for my project (Knight rider dash). That thing as like 24 or 30 of those displays in them. I may just contact one of the manufacturers and find out how hard it would be to get them to build the same physical unit but with common anode.
 
no luck there

Well, no luck with a responce from mfg. Anyone have a small code example or something? Im trying to wrap my brain around how to do this efficiently but Im comming up with squat. My application has these in a bargraph mode so there are points in time where it is possible that all 12 segments might need to be on. My current problems are 1: I am using pic basic (i know...) and 2: The pic is so busy trying to keep the LED's on that there isnt much time for it to execute any other code.
 
If you have hundreds of LEDs (30 displays * 12 LEDs) just drive them in pairs. Nobody will notice, even if it's running slow.

It's a lot of work, but the attached circuit could drive each LED on its own logic signal. Raise each input high to drive a given LED.

Unfortunately there are three problems:
1) the LEDs will have brightness changes when switching from LED1 to both to LED2.
2) the circuit has no tolerance for different LED forward voltages.
3) the logic and LED supply in this example is 7.5V. This probably means CMOS, like 4049.
 

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2: The pic is so busy trying to keep the LED's on that there isnt much time for it to execute any other code.
You just have to write your code correctly.

You have a main loop, right? Every microcontroller program has a main loop of some sort. At the top, or bottom of the loop, switch the LEDs to the next state. The loop should be running fast enough that it'll appear the LEDs are on steady.

So, if your loop currently looks like this:

Code:
main_loop
     do_one_thing
     do_something_else
     do_another_thing
     goto main_loop

change it to:

Code:
main_loop
     do_one_thing
     do_something_else
     do_another_thing
     update_leds
     goto main_loop

Or, if you're using a PIC that supports interrupts, you could use TMR0 to generate an interrupt that causes your code to update the LED strobing, then return back to whatever you're executing.
 
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