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Author Topic: NBv4 with neopixel random flickering issue  (Read 367 times)

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Offline raspeitia

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NBv4 with neopixel random flickering issue
« on: February 19, 2018, 08:22:41 AM »
Hi,

I have my NBv4 working with a blade of 71 (seventy one) 8mm neopixel leds soldered in a row.

The issue i have is random flickers at the top 6ish led area. The blade lights up fine, but randomly or on startup or shutdown, one of the leds will stay lit or flicker. Always around the top 6th one but not always the same led.

I was wondering if it could be a timing issue and wanted more information on the ls0 and ls1 values.

I have the NBv4 wired with the L1 and L2 pads joined to power the LED string and am using the 470 ohm resistor on the data line. I also added a 47uf 32v cap on the blade power leads. The LEDs I have are "APA-106" and are in GRB configuration on the data line.

Currently I have ls0=14 and ls1=28

I can see why changing the timing on the config file for the ls0 is done, but how does changing the ls1 value to "double" work?
Why do we do this?
Is this still the way to change the timing when we have L1 and L2 joined?


Any help to understand if my timing is the issue or how to properly adjust would be appreciated.

Thanks.

Ray A.
« Last Edit: February 19, 2018, 08:25:12 AM by raspeitia »

Offline erv

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Re: NBv4 with neopixel random flickering issue
« Reply #1 on: February 19, 2018, 10:34:09 AM »
Check your data sheet for your API 106 is the first thing to do.
If it happens in the string at a specific position it's probably due to one of the pixel being improperly wired or being damaged. You might want to put the data line resistor close to the beginning of the strip if it's not already the case to ensure that edges of the digital signal remains sharp.
Ls1 is usually the double of ls0 value. Dose timing values are in multiple of 25.2 nanosecond.

Offline raspeitia

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Re: NBv4 with neopixel random flickering issue
« Reply #2 on: February 19, 2018, 01:09:12 PM »
erv,

Yes, I have the resistor soldered directly to the first LED Data In lead. I also made sure that the power wires are not looping around the data wire in any way.

I can try narrowing down the LED if possible but they look to be random from that point up.

I reviewed the datasheet (see below) for the LEDs and I think the math checks out for the ls0 value. According to this it looks like should be 350ns, so 14x25.2 gives me 352.8ns

I tried different values just to test and 13 seems to work as well as 15, its just I was not sure that Ls0 was doing anything if I left it at 28.

How does the ls1 value of 28 affect the timing vs ls0?



Offline erv

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Re: NBv4 with neopixel random flickering issue
« Reply #3 on: February 19, 2018, 01:41:29 PM »
There are 2 timings to drive the pixels, hence ls0 and ls1

Offline raspeitia

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Re: NBv4 with neopixel random flickering issue
« Reply #4 on: February 19, 2018, 01:48:55 PM »
Ahhh. So is that what the second timing value (1360ns) on the datasheet is?

Would that mean that I need 53.9 for the ls1. But since the values can only be 5-50, then I should try 50?

Offline raspeitia

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Re: NBv4 with neopixel random flickering issue
« Reply #5 on: February 19, 2018, 05:53:56 PM »
so I tried
ls0=14
ls1=50

and no, the blade was jumping colors everywhere.

I went back to trial and error and it seems that for these LED the flickering is almost gone with
ls0=13
ls1=30

I'm going to replace the LED at the odd position to see if your suggestion of a corrupt LED might be what is causing the rest of the odd flickering near the top.

Thanks for the help erv and for making a cool controller.

Ray A.