Intermediate pixel guide

Welcome to the more intermediate guide on how pixels work.

If you haven't read the beginners guide please do so here is the link to that guide.

• Pixels a beginners guide

Which pixel is right for me?

In the first guide, pixels vs traditional lighting was covered, this should aid you in selecting a pixel profile. This will now expand on some of the rest mentioned in that section.

Smart vs dumb and how this applies to your show.

Dumb pixels as you know only take up 3 channels per strip so sequencing them is much easier, the major factor in going for these pixels is the cost vs future needs. While the dumb pixel stings, no matter the profile, are less expensive. Adding several of these may require several controller boards to get the color pattern your looking for. Their savings on the strings may be offset or even make them more expensive than going with smart pixels due to the number of controllers. Dumb pixels were the first pixel strings introduced, and generally are being replaced by the smart pixel. If you decide on the dumb pixel stings you will know why you chose these.

Smart pixels take up a lot of channels depending on how many pixels you use, making sequencing a lot more challenging (their are tools built into most sequencing software to help deal with the vast number of channels used in smart pixels). Smart pixels can be controlled like a dumb pixel string in that we can individually turn several pixels in a row the same color. If at some point in the future you are going to want to change from dumb pixels to smart pixels on a prop, eave, or window outline, due to the effects that smart pixels allow, the suggestion is to get the smart pixels and control them like dumb pixels. To change from dumb to smart at a later time means repurchasing the pixel strings and the controller boards. Right now smart pixel strings are about 10-30% higher in cost, the controller boards are about 50% more expensive, but as was stated above you may have far less controllers. When choosing smart pixels you understand the higher possible initial cost will allow the effects your wanting either now or in the future.

5 volt vs 12 volt what this really means.

In the electricity world wattage is everything, its how you are billed every month typically in kilowatt hour. This sounds like a big number but its really not. A watt of power is voltage times the amperage (current). Amperage is increased as resistance is decreased. In lighting when you decrease the resistance you increase the brightness, a 100 watt bulb is far brighter than a 40 watt bulb, the input voltage is still either 110 volts or 220 volts household voltage but the 100 watt has lower resistance so it glows brighter that's the difference between them, The 100 watt bulb uses up that 1000 watts in 10 hours, the 40 watt bulb would take 25 hours to use 1 kwh (kilowatt hour). Since resistance is determination of the brightness the 5 volt is much more power efficient. As the resistance is the same inside the pixel elements, 5 volts times that amperage is a smaller number than 12 volts times that same amperage. Since 5 volt is much more efficient why do we have 12 volt your asking. Well as electricity travels down a wire the wire has a small amount of resistance in it, the bigger around the wire the less resistance is felt (I know, not what you were thinking there right?). As voltage encounters resistance (both from the wire and the pixels themselves) a portion of it is consumed lowering the voltage available further down the wire. Since a pixel runs on about 3.3 volts (a built in resistor drops the input voltage to the 3.3 volts needed). With a 5 volt input we have very little wiggle room for that voltage drop before the voltage is no longer be able to correctly power the pixels. In a 12 volt pixel string we have a lot more wiggle room so longer runs are possible with the 12 volt input. We can hook strings of pixels together (both dumb and smart) but at some point the voltage is too low to properly power the pixels. To overcome this we can reintroduce the 5 volt or 12 volt (a reset button of the voltage so to say) at a point or points in longer runs, this is referred to as power injection. As you can see resistance plays a role in both amperage and voltage affecting the number of watts used in anything electrical. If you peeked at the wiring smart pixels wiki you saw at the beginning a general rule of thumb, power inject 5 volt pixels every 50 pixels, and on 12 volt pixels every 100. Depending on how long you want the pixel strings to be will better help you determine what voltage is right for you.

Whats up with these Protocols?

As stated in the beginners wiki there is a bunch of different protocols, mostly determining the right protocol for you depends on how "big" your show is or is going to get, and how future proof you want to be. At first we have only a "few" channels ranging from 16 for traditional lighting to a couple thousand for doing all smart pixels, all these channels need to be refreshed or resent out several times a second to keep the lights doing what you want them to do. Each protocol has so much data it can send out each second (baud rate) some of the original protocols used are around the speeds of early modems 16000 bits per second. These are wonderful for traditional lighting, since the protocol has been around a longer time its costs are generally low, pixels on the other hand have the need for several thousand or even several million bits to go out each refresh, so those early protocols are far too slow for pixels. The rate of refreshes determines how often the lights can change states (dim, brighten, or in pixels change colors). They eye can generally pick up anything slower than 23 times per second (think of flicker on a TV set) Most TV's refresh their picture 29-60 times per second. In computer controlled lighting you also want to maintain at least a 25 refresh per second rate or your effects will look to jump from element to element instead of flowing from element to element. We talk in electronics mostly in milliseconds (1000 milliseconds = 1 second) so 25 refreshes per second works out to about 40 milliseconds between them, if were sending that several thousand bites of data every 40 milliseconds we need several hundred thousand baud rates to keep up. Enter the newer and faster protocols, these can range from several hundred thousand to over one hundred million bits of data every second.

This will try to talk about the protocols in terms of speed from slowest to fastest and their pros and cons. Note: there are other protocols not listed here that generally are not used in the DIY community and will not be covered by this wiki.

Serial RS232 - This is the oldest and slowest protocol, it is not used in pixels due to its baud rate limitations.

Serial RS485 - This is the first usable protocol by pixels, serial data is put out either by the serial ports on the back of your computer (some modern computers have eliminated one or both of these so your computer may or may not have these) or on the USB (universal SERIAL bus) we need a piece of equipment to convert the serial data to RS485 protocol, typically these are either a plug in adapter using the serial ports on the back of your computer or a "dongle" on a unused USB port. Both of these function the same converting serial data to the RS485 protocol. RS485 is a standard that supports up to 32 drivers and 32 receivers on a single computer output. Its data rate can vary from 100kb/s to 10mb/s making it very flexible for use in large pixel displays. You will find that a lot of the commercial controllers use this (light o rama uses this protocol almost exclusively). The biggest draw back for this protocol is the 32 controller (universe?) limit, at first you may not need that many but as your show grows you may find you need more than 32. You can always add another dongle increasing your controller limit though. This is widely available and relatively inexpensive.

Renard ??? some clarification from the renard community here as i do not know this.

E1.31/ACN - This is a suite of protocols that is most commonly used to control theatrical lighting, audio and effects. ACN can be combined and configured with other standard protocols. It can be implemented on a variety of networks, typically using Ethernet (E1.31). This is a form of carrying data, but not the final form, meaning we need a bridge to have the DMX512 sent to the boards. Its rates can vary from 256kb/s to 100mb/s. This uses the same protocol as your internet connection on your computer. E1.31/ACN data is not recommended to be broadcast on your home wired or wireless network as the amount of data going through it will interrupt or bring your internet to a crawl. Instead we typically use a private network to run this protocol. Because this uses ethernet, a knowledge of ip addressing as well as mac addresses is needed to configure this, making this a little more difficult for a new person to grasp right away (unless your the I.T. guy). This being the newest protocol its availability is lower and costs are higher than using older technology. This can support over 16,000 universes making it a very future proof way to go.

All the protocols carry the DMX512 signal. DMX512 is a standard that describes a method of digital data transmission between computers and lighting equipment and accessories. It is the language for many solid state lighting boards. This is the signal that the boards use to turn the lights on or off and dim and brighten, but is not the native language of smart pixels. In a smart pixel board the dmx signal is converted to "pic" language that the pixels speak by a chip on the board.

In summary here you have computer to output (either serial or ethernet) to bridge (either a dongle on the usb for serial, or bridge for e1.31/acn) to board. Important controller boards are not universal, the protocol and controller board must match.

Note in some high density smart pixel boards the bridge is built into the board allowing direct connection to e1.31 networks.

Now lets see how all this newfound knowledge applies to the controller boards themselves.

TBA later or expanded on as people get to it :D