Help. Can' get equal color for all led strips

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andy_bu
 
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Help. Can' get equal color for all led strips

Post by andy_bu »

I have 3 stripes 144 leds each. If i start my program or standard test i have always the same problem beginning from 170-190 led.
The program begins to show another colors and begins to crash.
I tried with different platforms Uno and Mega but i have always the same problem.
I tried with 2 different adapters – 8A and 20A.
I tried to use another library – FastLED, but there i have the same problem. I can’t have that all leds have the same color.
I tried to reduce the brightness, but it does’t solve the problem.
If someone had the same problem and solved it, please answer.
Best regards
Andrey

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adafruit_support_bill
 
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Re: Help. Can' get equal color for all led strips

Post by adafruit_support_bill »

How are you powering the strip? With the 144 pixel strip you will have better results powering from both ends.

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andy_bu
 
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Re: Help. Can' get equal color for all led strips

Post by andy_bu »

I tried it for only one side.
I'll try it today.

Thanks for an answer.

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andy_bu
 
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Re: Help. Can' get equal color for all led strips

Post by andy_bu »

I tried to add the power for both sides, but i have the same result.
If i take the standard test it crashes in red color in first function on position 170-190.
Some leds in the stripe instead of to be red, get different colors.

Best regards
Andrey

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adafruit_support_bill
 
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Re: Help. Can' get equal color for all led strips

Post by adafruit_support_bill »

Please post photos showing your connections to the strips.

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andy_bu
 
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Re: Help. Can' get equal color for all led strips

Post by andy_bu »


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adafruit_support_bill
 
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Re: Help. Can' get equal color for all led strips

Post by adafruit_support_bill »

I can't see from the photos, are the strips connected as one long strip? (i.e. the output of one strip feeds the input of the next one)
Please post the code you are using.

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andy_bu
 
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Re: Help. Can' get equal color for all led strips

Post by andy_bu »

I think this image will be better,
i connect 2 stripes in one line.
First i connected the power only to the start of the first line, but another user of this
forum advised to connect the power to all sides.


For a test i use the standard adafruit library test, without any changes.
Just the number of leds
http://postimg.org/image/kx6faxhy3/
Best regard
Andrey

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adafruit_support_bill
 
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Re: Help. Can' get equal color for all led strips

Post by adafruit_support_bill »

For a test i use the standard adafruit library test, without any changes.
Just the number of leds
And the problem doesn't start happening until you increase the number of leds in the program beyond about 170?

If it is happening on a Mega, it is not a memory issue.
It could be a voltage drop issue. What is the voltage at the end of the last strip when running the test sketch?
It could also be a bad pixel. If you change the order of the strips, does the problem occur on the same pixel, or at a similar place on the other strip?

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andy_bu
 
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Re: Help. Can' get equal color for all led strips

Post by andy_bu »

I tried with 2 different adapters 8A and 20A.
I have 5 meter led stripes and it depends not which 2 of them i take.
If i take this program https://gist.github.com/Yona-Appletree/6490993,
i see that all leds are glowing.
But if i use something complex it does't work well.
Do you know other possibility?
Can i connect 3 stripes paralel to one pin?

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adafruit_support_bill
 
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Re: Help. Can' get equal color for all led strips

Post by adafruit_support_bill »

I tried with 2 different adapters 8A and 20A.
So it is not likely a power issue.
I have 5 meter led stripes and it depends not which 2 of them i take.
If i take this program https://gist.github.com/Yona-Appletree/6490993,
i see that all leds are glowing.
And it is not a bad pixel or strip problem.
But if i use something complex it does't work well.
Do you know other possibility?
I will check with some of the other engineers to see if they have any ideas.
Can i connect 3 stripes paralel to one pin?
A fan-out of 2 or 3 strips on one pin usually works.

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adafruit_support_rick
 
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Re: Help. Can' get equal color for all led strips

Post by adafruit_support_rick »

Check that you have a good common ground reference between the strips and the Mega

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andy_bu
 
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Re: Help. Can' get equal color for all led strips

Post by andy_bu »

Hi.
I proved the Gnd connection, it ok.
i think the problem can be in difference volt between Arduino and Led stripes.
Led stripes receives 5 volt and arduino block energy from computer.
Such a led stripes a very sensitive to voltage difference.
What can i do with this issue?
Can i use optocoupler or transistor to balance the voltage?

Best regards
Andrey

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slight
 
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Re: Help. Can' get equal color for all led strips

Post by slight »

just one fast thought:
be careful with more than 85 pixel...
--> some of the examples out there use a byte (uint8_t) as counter / array index or something similar..
and that woks only fine for 85pixel (255/3=85 --> every pixel needs 3byte.)
(i run into this with a test i did.. ;-) )

and for your power:
every stip of 1m needs about 10A - and you should power every meter from both sides - so that the 'current' only has to travel a maximal of 0,5meter of strip. ( the stip has a relative high resistants..)
and secondly - i saw in one of your photos - you use a DC-Hole Plug.. these are normally not designed to carry more than 2 or 5 Amps MAX... ( i checked the product sites and there is nothing mentioned.. - are there official limits? )

sunny greetings
stefan

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slight
 
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Re: Help. Can' get equal color for all led strips

Post by slight »

(sorry for the double post - i missed a part of your post)

if you are sure that you have 5V and these are stable (have you got some capacitor in your design? )
you can use the 5V pin on your arduino to power it from the same powersupply that powers your led-strips.
if your powersupply can not handle peaks of current well (flashing all leds to full white for example) that eventually the voltage can drop and your arduino will hopefully reset (or worst case freeze)

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