LED 16x32 Matrix: shining without Power

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Arduprog
 
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Joined: Tue May 27, 2014 2:57 am

LED 16x32 Matrix: shining without Power

Post by Arduprog »

Hello Adafruit,

I'm using the product ID420 16x32 Medium RGB LED matrix panel.
As you showed in your learning section I wired it up on a proto shield.

Now the strange thing:
When I powering the Arduino (uno) the matrix panel starts to shine - without powering the panel! It is not that bright as with Panel-power but it is just dimmed like I think it is bright enough.

1) Is this behaviour normal?
2) if yes - can anything blow up when not powering the ICs on long run?
3) where do the panel get the power from? Is it just from the date-pins power possibilities?

I wanted to send data to the panel al the day and just switch the power on of the panel when I needed it to shine. This is now oblolete.

But: A very nice panel - thank a lot for it!

Greetings,
Arduprog

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Franklin97355
 
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Joined: Mon Apr 21, 2008 2:33 pm

Re: LED 16x32 Matrix: shining without Power

Post by Franklin97355 »

Could you post clear, detailed pictures of both sides of your board showing any soldering you have done and the connections to it?

Arduprog
 
Posts: 4
Joined: Tue May 27, 2014 2:57 am

Re: LED 16x32 Matrix: shining without Power

Post by Arduprog »

IMG_3970.JPG
IMG_3970.JPG (149.68 KiB) Viewed 315 times
IMG_3967.JPG
IMG_3967.JPG (107.81 KiB) Viewed 315 times
Hi,
hopefully the pics are good. Pin1 of the cable-plug has a red sign.

Thanks a log!

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pburgess
 
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Joined: Sun Oct 26, 2008 2:29 am

Re: LED 16x32 Matrix: shining without Power

Post by pburgess »

This is normal. In the absence of a power supply, the matrix will try to run off the tiny bit of power coming from the data lines. Usually just red, and usually very dim.

Instead of cutting power to the supply, you'd instead need to clear the display. (using matrix.fillScreen(0))

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