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Old 04-24-2017, 12:47 AM
Charixfox Charixfox is offline
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Originally Posted by garyd9 View Post
Now that I've read up a bunch on the board, and the source, etc.. I have a few more questions. ;)

This might be basic electronics... (I have the feeling it is, but I'm missing something)... why bother connecting +5 to raw? From:

That leads me to believe that EITHER the board is powered from this pin (taking 5v from it - treating it as 5v IN) OR the board is powered from USB, in which case the RAW pin is 4.8v OUT (and can even be used to power something else as long as it's very low amperage.)
Is it absolutely necessary? No. Is it a Good Idea? Probably. The 5V from the hub to the controller are technically both the same rail from the PSU, just coming from separate places. However if the USB disconnects for whatever reason, resets, etc, the 5V from the hub will keep everything running.

Originally Posted by garyd9 View Post
If less than 6 fans were plugged into the hub, would it be possible to attach to the first unused fan connector (on the hub) and send the data OUT back to the ProMicro... and then use that data to determine how many LEDs actually existed?

From what I can tell, fastLED references the 1st LED in fan#2 as leds[12], and the 1 LED in fan#3 as leds[24]. In other words, the LEDs in multiple fans are treated as a single long strip (and not as multiple connected strips.) Obviously, I don't know the underlying protocol, but I'd imagine that FastLED sends out some type of signal saying "hey, set LED #14 to 0xff0000" and the 2nd LED on the 2nd fan turns red.

Somehow, the 2nd fan "knows" that it's LED's are addressable as #13 thru #24. It seems to me that whatever mechanism is used to determine that information could also be used to determine when the chain ends IF the data chain continues back to the micro pro board... and so the code could theoretically determine how many LEDs/fans are actually in the strip.

Of course, this assumes there might be some functionality within FastLED to accept that data and do something with it. (looking at the library reference, nothing jumps out at me... but I still have to wonder if the data could be extracted or not.)
Yes, but probably not really.
It's a cascade and latch system when it reaches the strip. Starting from nothing, the data reaches the first LED and is stored on it. The next one-LED segment of data is stored and the prior one is spat out to the next LED. When there is a long enough pause in the data stream, the LEDs will "latch" and start PWN-displaying the set data.

If there are three LEDs, FastLED sends #3 data to the strip, which gets stored on LED 1. Then it sends #2, and LED #1 spits the #3 data to #2 while it takes data for #2. Then it sends #1 and it gets bumped along so #2 sends the #3 data to #3, #1 sends #2 data to #2, and #1 gets its data. Then a "long" (5000 picoseconds or so, give or take a magnitude) pause causes them to stop listening for data and start displaying the results.

There is no concept of LEDs knowing which one they are and FastLED has to send the whole set every time it does anything at all. So sending the data back to FastLED would just end up giving the data back at the end. That being said, -technically- it might be possible to say "I started hearing incoming data after sending N segments of data, so I must have N LEDs attached in the loop". That would be VERY non-trivial however. ^.^

Originally Posted by garyd9 View Post
Some interesting ideas for different modes:

Use the LED lights to represent a configured timer. The PC software sets "timer" mode with a timeout of (for example) 30 seconds... and the LED animation is arranged to "spin" with a full revolution completed in 30 seconds (and then the full set flashing at expiration.)

All kinds of fun things could be accomplished with a thermistor or two attached... With multiple thermistors, a single fan could even show general temperature levels for multiple thermistors.

I wonder if it'd be possible to tap into the 3rd wire (tach signal) in a case fan (or water pump's fan connector) to show a "color" animation representation of the fan/pump speed. (Some testing would be needed to scale things, of course.)

This is going to be fun...

Take care
The timer idea would be a possibility.

As for Temp/Tach, I'm perhaps a weirdo on that matter. My super-fancy LED colors in my opinion should show me pretty things, not "Stay one color when everything is proper (cool) and change to a bad color that I hope to never see when things turn bad (hot)." I prefer interesting feedback over temp colors, since if things are going well, you would only ever see one color, or you'd end up desensitized to it from the fluctuations, or if it shows OMG colors, well, you have bigger things to worry about than pretty LEDs. :)
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