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Randy, LEDWiz question - CHECK IT OUT, youtube embedded video!!!!

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mccoy178:
Okay, if your product puts out a digital signal, could something like this be used?

Long link

http://www.analog.com/en/prod/0%2C2877%2CAD5641%2C00.html

mccoy178:
Randy, what type of output is needed for the LEDWiz to read?  Barcrest is willing to write the software for this, but he needs to know what kind of signal is required.

RandyT:

--- Quote from: mccoy178 on November 09, 2007, 02:32:10 pm ---Randy, what type of output is needed for the LEDWiz to read?  Barcrest is willing to write the software for this, but he needs to know what kind of signal is required.

--- End quote ---

Do you have a source for these parts?  We really need to try one.  Do you have one we can check to see how the comparators deal with the PWM output of the LED-Wiz?  Without knowing that, the software is, I'm afraid, pointless.

RandyT

mccoy178:
Here is some links to each products .pdf:

LM3915

LM3916

I have ordered a few of the LM3915 from digikey yesterday.

RandyT:

--- Quote from: mccoy178 on November 09, 2007, 04:35:56 pm ---Here is some links to each products .pdf:

--- End quote ---

Thanks.  I have seen these already.  Just to make sure I'm not misunderstood, what I don't know is what is happening at the input buffer stage of the device.  The schematic shows that this device is pretty much a "resistor ladder".  It works by virtue of the fact that each LED driver has the resistance of it's own resistor, plus the resistance of every other resistor lower in the ladder because they are in series.  This means that the first driver will take very little voltage to cause the LED to light, while the voltage requirements for the drivers that follow become greater the further up the ladder you go.

I've never tried running a PWM output into a resistor ladder, but I'm not convinced it would work.  However, if the buffer at the input of the chip does anything other than just pass it through, there might be a chance. It's going to take some experimentation and other components may be required.

RandyT

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