16x32 RGB LED matrix panel does not show rather than red

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kjoo
 
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Joined: Tue May 05, 2015 7:54 pm

16x32 RGB LED matrix panel does not show rather than red

Post by kjoo »

Hi, I just got 16x32 RGB LED matrix panel, wiring to my raspberry pi 1 and running the test as following tutorial.

https://learn.adafruit.com/connecting-a ... i/overview

I thought it is working OK at first place.
However, it only displays the color of red and no other colors at all.
I tested on the other raspberry pi 1 and it does same.

I will make sure power supply is OK just in case, when I got new tester arrived.
But, power cabling is very simple and not likely causing problem above to me. (if it does for some technical reason, I would like to know)

I tried to change the pin assign on example python code for some debug,
and it shows the rectangle shape changed.
I guess some pin is not getting any input at all or something?
(Again, not likely to me, because other pins seems working just fine )

The tutorial mentioned about level shifting chips, in order to fix some problem.
However, it does not say any schematics.

My question is

Is there any way to debug/fix the problem?
Should I try level shifting chips? Any schematics available for Pi/Chip/Panel combination?
Or try changing the panel first?

Any advises are appreciated.
Thanks!!

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pburgess
 
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Re: 16x32 RGB LED matrix panel does not show rather than red

Post by pburgess »

Red-only is usually an indication of a power supply problem (the LEDs are running off parasitic power from the data lines, and there's only enough current for red, which have the lowest threshold).

If you have a multimeter, first check the output from the power supply, confirm 5V is present. If so, then work your way up the line...confirm the there's 5V at the DC jack (use the two screw heads as test points), then on the back of the matrix.

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kjoo
 
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Re: 16x32 RGB LED matrix panel does not show rather than red

Post by kjoo »

Thanks for reply.

Now, it is acting very funny.
It shows full color dots on random position.
And running demo program makes display totally blank.

I tried to test few different power supply which has closer value to 5V / 2A.
It now does not show even red animation either.
However, when I swap the power supply (I do it own risk to save time)
It shows red dots animation again.

I will check all wiring again and get multi meter.

By the way could you tell me where 2 screws you mentioned are?
the one right center of the panel on both side?

I attached my wiring setup, if it could be any hint...

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kjoo
 
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Re: 16x32 RGB LED matrix panel does not show rather than red

Post by kjoo »

Problem resolved!

It seems when I swapped the power supply, everything was OK.
However, seems I broke 1 wire for GPIO.
After I changed false wire, everything works fine.

I am so glad seeing full color animation demo.(much better than red only)

Thanks!

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