Oh, the wondrous and exciting times of being a Start-Up! ** Choke, cough, ah-hem! **
...Actually, it HAS been fun, but the devil is in the details, right?
To get the ball rolling on the whole eCommerce process, including the boxing, shipping, paying tax (ouch) and handling returns and after-sales service, we wanted a ready-made portfolio of products to sell, to check at least one of the boxes off with the Easy button.
I knew at the end of 2021 that the great folks at Pace-O-Matic were going to help me with this new venture, and so I made it a priority to go to the Consumer Electronics Show in Las Vegas in early January of 2022. Companies from all over the world come to CES to show off their latest gadgets and innovations.
I met the partners of a Smart Home products company based in Shenzhen and Dongguan and I was really impressed with the Smart, Addressable LED technology they had developed for string lighting; like Christmas lights and such, right?
The key to Hysiri's technology was Multi-Drop networking. Sounds dry and technical, I know. But normally, you see, "addressable" LEDs are not really addressable in the traditional sense. Instead, the LEDs are cascaded in what is called a Daisy-Chained arrangement as shown here in this diagram from microcontrollerlabs.com
As you can see, the data comes into the top LED on the right side to the DIN (Data In) pin, and it stops right there. That signal goes no further in its natural state. Instead, IF it is the data for an LED, and no data for the current frame to be displayed has been received by this first LED, it "absorbs" that data for itself, since it tells the LED the R,G,B and sometimes gamma-corrected brightness values for the LED to display (often gamma is internally calculated inside the LED).
If that first LED already has data for this frame, then the data received is regenerated and sent out on the DOUT pin to be introduced to the second LED, where the process is repeated.
There are some good features of this scheme:
The data does not have to travel a long distance, like all the way to the end of a string. It only has to get to the first LED, where it gets "freshened" if it has to move on.
The LEDs themselves do not store an address that has to be "globally" unique within the string. If an LED goes bad, it can be replaced into the same point in the string and everything still works as before.
The Controller only needs to know how many LEDs are in the string to make sure all the LEDs get data. There is no absolute need for mapping, although to get geophysical location data, that would still be needed.
As long as power is properly supplied, more than 1000 LEDs can be driven at a decent frame update rate. The versions of LEDs that use only a Data line with no Clock signal are potentially more limited, and the rate at which data goes out is fixed in most all current Data-Only designs at about 800Khz.
On the Down-Side:
Since the data has to be regenerated by a working LED, if the LED's microcontroller or connections to it get knocked out, the entire string after that goes dead, kind-of like the old mini lights that are series-connected, but at least these LEDs tell you where your problem is. There are actually LEDs that add a whole second Data line, as a backup that goes around a bad LED, but that adds cost.
There is no way to create true stubs or dead-ends and continue the string. At that point, it takes an addition channel of data from the controller. The data has to daisy-chain to the next LED, even if that means an extra wire going back up the stub to continue to the next stub. It makes it more expensive to do Curtains or Icicle lights, for instance, but not impossible.
Not that it makes that much difference, but on an efficiency point, to talk to LED 100, you have to talk to every LED up to 100 to get data to it. There is no "Direct" access by the controller to that LED 100. So if an animation frame rate could be improved by only updating a limited number of LEDs, that quickly becomes difficult to improve upon.
Hysiry's RGBHUB
The technology I saw at CES 2022 was new to me. I saw a light curtain where there was a "bus" of heavy wire going along the top and then true stubs dropping down every 3" or so, to dead-ends.
With only 3 wires in the bus and 3 wires in the drops, I deduced this was NOT a daisy-chained system. I was also impressed by the bonded and epoxied LED technology. Light comes out brightly from all sides of the bead, so the wire itself can twist without impairing the display of color.
RGBHUB's benefits:
Multi-Drop networking allows true stubs and dead-ends to exist, with a central distribution point possible
Every LED has a GUID (Globally Unique Identification number), and that GUID is Geo-Located in the string since the address is programmed during string assembly / bonding.
Full random access to any LED is now possible
Simplified electrical properties reduce cost, and allow a "bad" LED without disrupting the rest of the assembly
Since the LED simply taps power and signal, only the insulation of the bus wire has to be stripped back a little. This allows the wire to retain that vast majority of its tensile strength.
Supports the concept of an all-LED Broadcast and Multicasting.
While no system has all the best of everything, this is a step in the right direction, and the implementation of the electronics has really been impressive. No termination resistors are needed and no ringing problems seem to exist. Electrically, the strings are much quieter, with less EMI / RFI than others I have tested. And I do have a rather extensive test bench set up.
I look forward to my next post, where we'll dive into some of the LED products. I will try to be less wordy, with more pics, I promise!
Chris
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