What is the longest distance between ws2812 pixels that can be achieved? how far have you tried?(I know ws2812 is an RGB led with built-in ws2811 IC) ws2812 and ws2811 use i2c serial communication and I’ve read that it can not go further than 1 foot (30cm) but to test it I connected 5 leds with ws 2811 IC’s with a distance of 1 meter between each and then I connected it with 5 meters of cable to a strip with 300 ws2812 leds and I ran the demoReel100 with no problem!
The datasheet states 10m before any amplification is necessary. Never actually tested this myself but may be doing so soon.
I have managed to get close to 30 feet (about 9 meters) of 3-wire 22awg cable between 2 WS2812. It worked perfectly but at the far end I had only 1 WS2812 LED on full white and I measured about 4.7Vdc so a 0.3Vdc voltage drop after that 30 feet.
If I added just a few more WS2812 LEDS at the far end, it probably would not work due to excessive voltage drop on the 5Vdc wires. Note that the data signal is regenerated by the WS2812 but not the 5Vdc supply voltage.
Normally, you should never let the 5Vdc drop below 4.5Vdc anywhere along your strips as that is the lower limit of the Operating voltage range specified by the WS2812 manufacturers. You could manage to get it ‘somewhat working’ at lower voltages but then you are in ‘uncharted’ territory and are not allowed to complain if it ‘acts funny’ !!
There are 2 ways to read this question. The word “longest” could be taken in the sense of the Guinness Book of World Records, or it could mean something akin to conservative engineering practice considering “worst case” scenarios, perhaps even factoring in temperature and likely variation in WS2812 controller chip fabrication.
@Jarrod_Wagner yes the datasheet says 10m but as @PaulStoffregen mentions I want to know the distance that can practically be achieved in outdoor applications.
I’ve ordered modules with 3 rgb leds controlled with a ws2811 chip (12V) I think individual IC’s do reshaping the signal better (?).
@JP_Roy I think the last LED that you say remains white is not because of voltage drop. I think 4.7 is pretty 5V !
one more thing, which pixel do you think is more immune to noise? ws2811 (I2C communication) or ws2801 (ISP communication)?
@Ahmad_Sajadian You did not understand my comment… the voltage dropped to 4.7V because that pixel was set to full brightness white. That pixel was fully operational and I could set it to any color and brightness.
Note that I use full brightness white because that demands the highest possible current (about 45 milliamps for a WS2811/WS2812) and this is how I test that my power distribution is up to par !!!
And NO… 4.7V is not pretty 5V !!!
As I mentioned, you should never let any point in your 5Vdc distribution wires and strips to drop below 4.5Vdc.
Note that 4.7V is pretty closer to 4.5V than it is to 5.0V !!
@JP_Roy I thought I read other posts that say we should assume 60 mA for full white. You mentioned 45 mA. Do the WS2812’s have different specs? (I’m using WS2812B’s and would love to find out they draw fewer amps!)
Hi @allanGEE , 45 ma is an actual current measurement I made on a number of different WS2811 / WS2812 / WS2812b devices.
I have never measured 60 ma on any of them but honestly, it is not a bad idea to use that 60 ma number in power calculations as it automatically gives you some extra headroom in your PSU selection and that is never a bad idea.
For example, I built a 8X8X8 cube with WS2811 and 8mm RGB LEDs. That is 512 RGB LEDs.
If you take 512 X 45 ma that is about 23 Amps
If instead you use 512 X 60 ma that is about 30 Amps.
Well the 5Vdc PSU that I used for this build is a 150W PSU ( 5Vdc / 30 Amps ) !
@JP_Roy Good thoughts and advice!
@JP_Roy Yes, I misunderstood your comment.