Go Down

Topic: ws2812b reverse polarity...only first works (Read 367 times) previous topic - next topic

uzer123

i have to reconnect the cables..it was a little dark..and my bad, i connected 5V to GND and reverse of the ws2812b ledstrip.

i heard a noise of "something is going wrong" and i close the power.

when i connected the correct one, i see that the first led works perfectly (i control it through a web server), but all the other are dead...

i multimeter and see that the 5V power is distributed correctly..

is it any way the data line or something is destroyed..so even the first led working fine, it cannot send the data?

and how i check? i tried giving data signal in the middle (i dont know if this can work normally) but nothing changed..

its a hard to solder/cut area..so i want the least invasive method..

Grumpy_Mike

Quote
is it any way the data line or something is destroyed..so even the first led working fine, it cannot send the data?
Long shot but possible.

Quote
and how i check? i tried giving data signal in the middle
Did you disconnect the input to the LED from the previous one? If so that will not work with a good strip.

Quote
so i want the least invasive method
Throw the strip away and buy a new one.
Alternatively cut the first led out and try again. Go through the whole strip like this and it will fit into the trash can better.

uzer123

Quote
Did you disconnect the input to the LED from the previous one? If so that will not work with a good strip.
yes, i let the power of the first one (but i have checked that the "middle" led had 5V), and disconnected the data from the first, and send it to the "middle".. But if the whole ledstrip can be divided..why this "trick" doesnt work?
is there any way the data signal go backwards?

my whole theory is that i find very strange to have the first led working fine..but all the other ledstrip (about 80 leds) is burned..

Paul__B

Alternatively cut the first led out and try again. Go through the whole strip like this and it will fit into the trash can better.
+1 for that!

Precious!  :smiley-lol:

Grumpy_Mike

#4
Apr 30, 2020, 11:57 am Last Edit: Apr 30, 2020, 11:58 am by Grumpy_Mike
When I said:-
Quote
Did you disconnect the input to the LED from the previous one?
I meant the data input to the one in the middle you tested not the first LED.
Of course all LEDs should be powered but the data out of the next to middle LED should be disconnected from the data input of the middle LED and the data signal out from the Arduino connected to the data input of the middle LED.

Quote
is there any way the data signal go backwards?
No, but the output from an LED can drag down any input you inject mid stream.

Quote
my whole theory is that i find very strange to have the first led working fine..but all the other ledstrip (about 80 leds) is burned..
That could be because the first LED is connected to the Arduino and the ESD diodes could have saved it from the reverse polarity that killed the rest of the strip.

DrAzzy

#5
Apr 30, 2020, 12:12 pm Last Edit: Apr 30, 2020, 12:14 pm by DrAzzy
Sad to say, the string is probably trash.

Hopefully it wasn't such a large string that it's too expensvie of a lesson for you to absorb - but you have now learned that when you make a project that must be assembled and disassembled in adverse circumstances, polarize all the connectors so that they cannot possibly be plugged in backwards.

 I make strings of lights that get assembled and disassembled at parties. And my friend brought his own huge light installation too. One of us used polarized plugs, so there was no way that they could possibly be connected wrong. The other one of us did not. He was stone cold sober when he put up his lights. I, ah, I may not have been.

He trashed his lights by connecting the power backwards when setting them up. My lights have now gone to firefly twice, and at least half a dozen weekend air-bnb-filling ragers, and none of them have failed. I don't even put them up myself most of the time, I let randos do it - and it's always fine, because the connectors physically cannot be connected wrong. Always use polarized connectors!
ATTinyCore for x4/x5/x61/x7/x8/x41/1634/828/x313 megaTinyCore for the megaavr ATtinies - Board Manager:
http://drazzy.com/package_drazzy.com_index.json
ATtiny breakouts, mosfets, awesome prototyping board in my store http://tindie.com/stores/DrAzzy

Qdeathstar

#6
Apr 30, 2020, 01:59 pm Last Edit: Apr 30, 2020, 02:03 pm by Qdeathstar
ws2812b strips have polarity protection, so something else is wrong. suggestions include your microcontroller is damaged or you have a coding issue.

https://cdn-shop.adafruit.com/datasheets/WS2812B.pdf
A creaking creeping shadow
stiff against the freezing fog
glares at a tickless watch.

Time has failed him -- all things shall pass.

uzer123

#7
Apr 30, 2020, 06:20 pm Last Edit: Apr 30, 2020, 06:21 pm by uzer123
thank you for all the answers..
before read..see the video here

i have some new findings..the good thing is that only 22 of 80 leds are dead.. the rest working fine..
although i cannot answer these findings..

what i have tried:
1) as i mentioned: put power to the first led, multimeter across the strip..the power is distributed fine.
disconnect the data line from the first LED and connect it across the ledstrip. Nothing is working

(strange  because
Quote
No, but the output from an LED can drag down any input you inject mid stream.
there is there no data from the "previous" leds.

Also:
Quote
That could be because the first LED is connected to the Arduino and the ESD diodes could have saved it from the reverse polarity that killed the rest of the strip.
im missing something? i use external power.. the esd diode is where? inside every led or mcu?

2) what worked: because i wanted to make a square shape with the ledstrip, i had cut it in 4 pieces..
i connected every piece with 3 wires..
so in order to test easier, i disconnected the first piece (the 22 leds) completely, and connect the 23th to be the first one. BOOM, the rest of the ledstrips (80 LEDS - 22 LEDS of the first piece working fine)..

i cannot understand why it couldnt work when i moved only the signal line..

3) i connected the first piece of "burned" LEDS to the end of the good piece..
results: it cannot work in no way..
i start cutting pieces..none is working..(i cut 1-2 leds from the beginning..the tried only the last..nothing

good thing is i will replace only the first piece..bad thing is that i cannot understand why the ledstrip "choose" to burn until the wire connection..


Quote
One of us used polarized plugs, so there was no way that they could possibly be connected wrong. The other one of us did not. He was stone cold sober when he put up his lights. I, ah, I may not have been.
true lessons..paid little..
usually im extremely careful with this kind of things.. now i was a bit unlucky also (the ledstrip had a red-green color for power..and white for GND.. i didnt see the red part of power line..and i usually use white as power alternative color)..
anyway..
i use this for this power line..i dont know any trick to polarize it

Quote
ws2812b strips have polarity protection, so something else is wrong. suggestions include your microcontroller is damaged or you have a coding issue.
i know there is polarity protection..maybe mine its not best quality.
no way its microcontroller issue or code..youll understand in the video..
i also didnt change the code on this MCU after the accident

larryd

From the data sheet:

" Intelligent reverse connect protection, the power supply reverse connection does not damage the IC."

But only the shadow knows.



No technical PMs.
If you are asked a question, please respond with an answer.
If you are asked for more information, please supply it.
If you need clarification, ask for help.

Qdeathstar

Use jst connectors, the are polarized and usually are preinstalled on the strips.
A creaking creeping shadow
stiff against the freezing fog
glares at a tickless watch.

Time has failed him -- all things shall pass.

Paul__B

From the data sheet:
" Intelligent reverse connect protection, the power supply reverse connection does not damage the IC."
22 of the LEDs were presumably asleep, and didn't realise what they were supposed to do intelligently.  :smiley-roll:

uzer123

Quote
22 of the LEDs were presumably asleep, and didn't realise what they were supposed to do intelligently.  :smiley-roll:
hehe..not so intelligent at the end..

ill try to get a refund for the not so intelligent 22 leds..
not for the leds..but for the time i spent find that they werent so intelligent after all..

Grumpy_Mike

#12
May 01, 2020, 10:12 pm Last Edit: May 01, 2020, 10:13 pm by Grumpy_Mike
Quote
im missing something? i use external power.. the esd diode is where?
Inside the Arduino's processor.

Quote
there is there no data from the "previous" leds.
There is a SIGNAL from the previous LED, even if this is a permanent HIGH or LOW. This will block a real signal from getting into the LED.

Quote
i cannot understand why it couldnt work when i moved only the signal line
Looks like either power and ground were burnt out. Did you check the burned strip for continuity of the power rails start to end?

As to Intelligent reverse connect protection this is just wishful thinking. It doesn't say what signals are protected. It could just apply to the data signal. Also to be "Intelligent" decisions have to be made and in order to do that the chip has to be powered correctly. This so called data sheet was probably written by someone who thinks they have a better grasp of the English language than they actually have. In my view this is not a data sheet, it is just a piece of marketing flam.

 


Go Up