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--- tutorials:products:pixel36mm:index.html [2012/01/27 17:37]
pburgess
+++ tutorials:products:pixel36mm:index.html [2016/01/28 18:05] (current)
@@ Line 62: / Line 62: @@
 The WS2801 chip is the same as in our 12mm pixels, so any software that works with the smaller pixels can also control these larger versions!
 ==== Wiring  ====
-The nice thing about these pixels is that they are digitally controlled. That is, even though there are only two data lines (clock/data inputs), you can put as many pixels as you'd like in a row and each one is controllable.
+The great thing about these pixels is that they're digitally controlled…that is, even though there are only two control lines (data and clock inputs), you can put as many pixels as you'd like in a single long strand, yet each one remains independently controllable.
-It is important to note that even though it looks like the 4-conductor ribbon is continuous, it isn't! The ground and 5V lines are shared but the two data **input** pins go to a microcontroller and the other side has two data **output**s.
+Though it looks like the 4-conductor ribbon cable is continuous, //it isn't!// The ground and 12V lines pass through from one pixel to the next, but the two data control lines are different on the input and output sides. The input side goes to the LED driver chip, which then drives its own output to the next pixel in the strand.
-[[http://www.ladyada.net/images/rgbpixels/20mmledpixeltop.jpg|{{  http://www.ladyada.net/images/rgbpixels/20mmledpixeltop_t.jpg?nolink&500x199  |}}]]
+When connecting these pixels to a microcontroller, make sure you're connecting to the strand's **input** pins! On these large pixels, it's easy to spot: examine the circuit board, looking for the "IN" label and an arrow indicating the direction of data flow. If connecting multiple strands together, make sure the output of one strand goes to the input of the next.
-When connecting to a microcontroller make sure you are connecting the **input** pins to the microcontroller! Best way to tell is to look at the dots and find the arrow. In the large dots above, the arrow is in the top right corner. The inputs are on the left and the signal passes to the right. If you want to connect multiple strands together, make sure input goes to output.
+{{ :tutorials:products:pixel36mm:36mmwiring.jpg?nolink& |}}
-Wiring is pretty easy since there are only 4 wires. The only important thing is that unless you are sure you will be using only a few of the LEDs at a time, you should not try to power the strip from the 5V on the Arduino. The Arduino is only mean to drive about 500mA of current, and as we saw earlier, a strand can take 1000mA or more if on! For that reason, we suggest powering with an external regulated 5V supply.
+Wiring is pretty easy since there are only 4 wires. The only important thing is that you should not try to power the LED strand from the Arduino's 5V line — these LEDs require a dedicated 12V source separate from the microcontroller.
-For **LPD6803** Pixels, use this diagram with Red going to +5, Green going to digital 3, Yellow going to digital 2 and Blue going to Ground. **WS2801 wire colors will be different, see below!**
+Use this diagram with the red wire going to +12V from the power supply, green (serial clock) to Arduino digital pin 3, yellow (serial data) to digital pin 2, and black to both the ground connection on the power supply and any available GND pin on the Arduino.
-{{  http://www.ladyada.net/images/rgbpixels/arduinowiring.gif?nolink&576x467  |}}
+{{ :tutorials:products:pixel36mm:arduinowiring12v.png?nolink& |}}
-Just make sure to 'share' the ground pin, and triple check that you have the voltage polarity right so that ground is 0V and power is 5V. For the arduino library we wrote, you can use any two pins.
+Our Arduino library (explained below) can use any two pins, but the examples are written to use pins 2 and 3 as above.
-=== Extra special note for WS2801 pixels ===
+==== Download ====
-**PLEASE NOTE: THE WIRE COLORS SOMETIMES CHANGE FROM BATCH TO BATCH! Do not assume the wire colors are 'logical' or the same for each strand. Double check by looking at the first input pixel!**
+To download the Arduino library, [[https://github.com/adafruit/Adafruit-WS2801-Library|visit the repository on GitHub]].
+Click the DOWNLOAD ZIP button near the upper left, extract the archive and then rename the uncompressed folder to ''Adafruit_WS2801''. Confirm that this folder contains the files ''Adafruit_WS2801.cpp'' and ''Adafruit_WS2801.h'' and the ''examples'' folder.
-If you have 12mm pixels you may have newer WS2801 or older LPD6803 pixels. You should check the pixel to verify what chip is inside. This is pretty easy, for the WS2801's you'll see it written on the PCB. You can also check your kit packaging.
+Place the WS2801 folder inside your Arduino ''Libraries'' folder. You may need to create this folder if it does not yet exist. In Windows, this would be ''(home folder)\My Documents\Arduino\Libraries'' and for Mac or Linux is ''(home folder)/Documents/Arduino/Libraries'' [[http://www.ladyada.net/library/arduino/libraries.html|We also have a tutorial on library installation]].
-{{:tutorials:products:rgbledpixel:ws2801pixel.jpg?500|}}
+After installing the Adafruit_WS2801 library, restart the Arduino IDE. You should now be able to access the sample code by navigating through menus in this order: File->Sketchbook->Libraries->Adafruit_WS2801->strandtest
-Here you can see the WS2801 written on the PCB. Another really annoying thing is that like we mentioned, the wire colors for the WS2801 pixels can be 'non-intuitive'. For example the first batch of WS2801 we got had **Data** wire blue, **Clock** wire red, **Ground** wire white, and **5V** wire black. You can determine the wiring for sure by holding up the pixel as shown in that photo and noting that the wire order is Data, Clock, Ground, +5V (this is not the same as LPD6803, see the diagram above for LPD6803 wiring!) Sorry about that!
+==== Code! ====
-==== Code!  ====
+Let's look through the strandtest example code. To use the library in an Arduino sketch, you'll first need to globally declare a Adafruit_WS2801 object to talk to the strip. It is invoked with three variables: the number of pixels and the data and clock pins:
-=== LPD6803 pixels ===
-The code to drive these dots is fairly simple, except that the PWM pin and the data clock pin is shared which means that you can't just stick the PWM pin on a hardware timer output because then its not possible to use it for the data clocking.
-Instead, the library uses an interrupt that goes off every few milliseconds. If there is data to be updated on the strip, it sends that data. If not, it just pulses pin to keep the PWM going.
-**Note that the interrupt uses timer 1 which means the pin 9 and 10 PWMs will not 'work' for servos, please use a 'software servo' library!**
-This code is heavily based off of [[http://www.bliptronics.com|bliptronics']] original code except we library-ized it and trimmed it down. [[https://github.com/adafruit/LPD6803-RGB-Pixels|You can download the library from github]], [[http://www.ladyada.net/library/arduino/libraries.html|then follow our library installtion procedure.]]
-Once you've rebooted, load up the **strandtest.pde** example sketch, we'll go through the most important parts.
-First up, you'll need to make an library object to talk to the strip. It is initialized with three variables, the number of pixels and the data/clock pin. You can change these later.
 <code C>
-// Set the first variable to the NUMBER of pixels. 20 = 20 pixels in a row
+int dataPin  = 2;
-LPD6803 strip = LPD6803(20, dataPin, clockPin);
+int clockPin = 3;
-</code>
-Next we will set up the strip in the **setup()** procedure.
-<code C>
-void setup() {
-  // The Arduino needs to clock out the data to the pixels
-  // this happens in interrupt timer 1, we can change how often
-  // to call the interrupt. setting CPUmax to 100 will take nearly all all the
-  // time to do the pixel updates and a nicer/faster display,
-  // especially with strands of over 100 dots.
-  // (Note that the max is 'pessimistic', its probably 10% or 20% less in reality)
-  strip.setCPUmax(50);  // start with 50% CPU usage. up this if the strand flickers or is slow
-  // Start up the LED counter
-  strip.begin();
-  // Update the strip, to start they are all 'off'
-  strip.show();
-}</code>
-**setCPUmax()** configures the timer 1 interrupt that PWM's the strand. You can change this from 0 to 100, it runs in the background. The 'max' is calculated assuming the longest possible timing (when sending data) so its a big pessimistic. 50% should be plenty, you can mess with this to make the strip more or less 'flickery' You can change this 'on the fly' so for example set it to 0% just before doing a bunch of Ethernet stuff, then back to 50% later.
-**begin() **actually starts the interrupt
-**show()** is what updates the strand display. You'll need to call it after setting any colors to see the updates. This way you can change the entire strip at a time (it takes the same amount of time to change one pixel as it does for an entire strip because the full strip data must be shifted out at once)
-Last, we'll look at an example function, colorWipe. This creates a 'chase' that fills the strip up with a color. It is basically a loop that increments through every pixel (which you can conveniently get by **numPixels()** ) and sets the pixel color of that pixel (incremented with **i**) to the color **c**. In this case the color is stored in a 16 bit variable. The strip output is then updated with **show()**. Finally there is some delay (otherwise this would happen instantly)
-Below that is a little helper that takes 8 bit red green and blue and bit-mashes them into a 15 bit color. This means that the 'max' value for each color is 31.
-<code C>
-// fill the dots one after the other with said color
-// good for testing purposes
-void colorWipe(uint16_t c, uint8_t wait) {
-  int i;
-  for (i=0; i < strip.numPixels(); i++) {
-      strip.setPixelColor(i, c);
-      strip.show();
-      delay(wait);
-  }
-}
-/* Helper functions */
-// Create a 15 bit color value from R,G,B
-unsigned int Color(byte r, byte g, byte b)
-{
-  //Take the lowest 5 bits of each value and append them end to end
-  return( ((unsigned int)g & 0x1F )<<10 | ((unsigned int)b & 0x1F)<<5 | (unsigned int)r & 0x1F);
-}
+// Set the first variable to the NUMBER of pixels. 25 = 25 pixels in a row
+Adafruit_WS2801 strip = Adafruit_WS2801(25, dataPin, clockPin, WS2801_GRB);
 </code>
-For example, in the **loop()** we call colorWipe(Color(31, 0, 0), 50) which will fill the strand with only-full-red light, pausing about 50 milliseconds between pixels.
+The last parameter there, ''WS2801_GRB'', is required when using these 36mm pixels (otherwise red and green will be reversed). You do NOT need this parameter if using our 12mm pixels.
-<code C>
+Next, we initialize the strip in the ''setup()'' procedure:
-  colorWipe(Color(31, 0, 0), 50);  // red fill
-  colorWipe(Color(0, 31, 0), 50);  // green fill
-  colorWipe(Color(0, 0, 31), 50);  // blue fill
-</code>
-=== WS2801 pixels ===
-This code is very similar to the LPD6803 but simpler because we do not need to use the CPU to update the pixel clock constantly.
-The code to drive these dots is even simpler, you don't need to worry about any timers, use any two pins you'd like! You can use anything that requires timer 1 like the servo libraries.
-[[https://github.com/adafruit/WS2801-Library|To download, visit the repository on Github.]] Click the DOWNLOADS button in the top right corner, rename the uncompressed folder WS2801. Check that the WS2801 folder contains WS2801.cpp and WS2801.h
-Place the WS2801 library folder your <arduinosketchfolder>/libraries/ folder. You may need to create the libraries subfolder if its your first library. Restart the IDE. [[http://www.ladyada.net/library/arduino/libraries.html|We also have a tutorial on library installation]]
-Once you've rebooted, load up the **WS2801->strandtest.pde** example sketch, we'll go through the most important parts.
-First up, you'll need to make an library object to talk to the strip. It is initialized with three variables, the number of pixels and the data/clock pin. You can change these later.
 <code C>
-// Set the first variable to the NUMBER of pixels. 25 = 25 pixels in a row
+void setup() {
-WS2801 strip = WS2801(25, dataPin, clockPin);
-</code>
-Next we will set up the strip in the **setup()** procedure.
-<code C>
-void setup() {
-  // Start up the LED counter
   strip.begin();
-  // Update the strip, to start they are all 'off'
+  // Update LED contents, to start they are all 'off'
   strip.show();
 }</code>
-**begin()** initializes the library and sets all the pixel colors to off.
+''begin()'' initializes the library, while ''show()'' refreshes the displayed colors of the LEDs. You'll need to call ''show()'' after changing any pixel colors to see this reflected in the LEDs. This way you can change the entire strip at one time (it takes the same amount of time to change one pixel as it does for an entire strip, because the full strip data must be issued regardless).
-**show()** is what updates the strand display. You'll need to call it after setting any colors to see the updates. This way you can change the entire strip at a time (it takes the same amount of time to change one pixel as it does for an entire strip because the full strip data must be shifted out at once)
+Let's look inside an example function, ''colorWipe()''. This creates a 'chase' sequence that fills the strip up with a color. It is basically a loop that increments through every pixel (which you can query with the ''numPixels()'' function) and sets the color of each (incremented with ''i'') to the value passed (''c'' — colors are expressed as a 32-bit variable type, though only the bottom 24 bits are used). The strip output is then updated with ''show()''. Finally there is some delay (otherwise this would happen instantly).
-Last, we'll look at an example function, colorWipe. This creates a 'chase' that fills the strip up with a color. It is basically a loop that increments through every pixel (which you can conveniently get by **numPixels()** ) and sets the pixel color of that pixel (incremented with **i**) to the color **c**. In this case the color is stored in a 32 bit variable but uses only the bottom 24 bits. The strip output is then updated with **show()**. Finally there is some delay (otherwise this would happen instantly)
+Below that is a helper function that converts a color from separate 8-bit red, green and blue values into a combined 24-bit value (suitable for passing to ''colorWipe()''). The brightness range is from 0 (off) to 255 (max brightness).
-Below that is a little helper that takes 8 bit red green and blue and bit-mashes them into a 24 bit color. This means that the 'max' value for each color is 255.
 <code C>
@@ Line 245: / Line 146: @@
   return c;
 }
 </code>
-For example, in the **loop()** we call colorWipe(Color(255, 0, 0), 50) which will fill the strand with only-full-red light, pausing about 50 milliseconds between pixels.
+For example, in the ''loop()'' function we call colorWipe(Color(255, 0, 0), 50) which will fill the strand with full-brightness red light, pausing about 50 milliseconds between pixels.
 <code C>
@@ Line 255: / Line 155: @@
   colorWipe(Color(0, 0, 255), 50);  // blue fill
 </code>
-==== Download  ====
-=== LPD8603 library ===
-We have an Arduino lirbary that can be fairly easily ported to any microcontroller with two digital output pins and a interrupt timer. This code is heavily based off of [[http://www.bliptronics.com|bliptronics']] original code except we library-ized it and trimmed it down.
-[[https://github.com/adafruit/LPD6803-RGB-Pixels|You can download the library from github]], [[http://www.ladyada.net/library/arduino/libraries.html|then follow our library installation procedure.]]
-**Dont forget that this library uses an interrupt on timer 1 which means the pin 9 and 10 PWMs will not 'work' for servos, please use a 'software servo' library!**
-=== WS2801 library ===
-[[https://github.com/adafruit/WS2801-Library|To download, visit the repository on Github.]] Click the DOWNLOADS button in the top right corner, rename the uncompressed folder WS2801. Check that the WS2801 folder contains WS2801.cpp and WS2801.h
-Place the WS2801 library folder your <arduinosketchfolder>/libraries/ folder. You may need to create the libraries subfolder if its your first library. Restart the IDE. [[http://www.ladyada.net/library/arduino/libraries.html|We also have a tutorial on library installation]]

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