LPD8806 LED strip-- code question

by howardb on Sat Mar 30, 2013 11:56 am

I am using the LPD8806 LED strip with the strandtest.pde that uses LPD8806.h and LPD8806.cpp libraries. The program runs successfully (even though is a hardware failure occurred recently after I got the LED strip and adafruit has generously offered to replace).

Anyway, I want to modify the strandtest code. I am a beginner at C programming. The three files included to run the strandtest program calls a function “strip” (strip.begin, strip.show strip.setPixelColor). I cannot find this function in the pde sketch or the LPD8806 .h or LPD8806.cpp libraries.
Can anyone tell me where the strip function is defined?
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Re: LPD8806 LED strip-- code question

by adafruit_support_rick on Sat Mar 30, 2013 12:28 pm

'strip' is a programming "object" which represents your LED strip, not a function. 'begin', 'show', and 'setPixelColors' are the functions, and they located in the LPD8806 library.

Near the top of the strandtest sketch, you'll see this line:
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LPD8806 strip = LPD8806(32, dataPin, clockPin);

What that does is to create an "object" called 'strip', and it tells the 'strip' object that it is going to be controlling 32 LEDs, which are connected to 'dataPin' and 'clockPin'.

dataPin and clockPin are defined a few lines earlier:
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int dataPin = 2;   
int clockPin = 3;


You could have a second strip of, say, 16 LEDs connected to pins 4 and 5. In that case you would declare second 'object' to represent the second LED strip:
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int secondStripDataPin = 4;   
int secondStripClockPin = 5;  LPD8806 secondStrip = LPD8806(16, secondStripDataPin, secondStripClockPin);


When you call a function like show(), you reference the LED strip you want to perform that function on:
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strip.show();  //perform show function on first strip only
secondStrip.show();   //perform show function on second strip only
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Re: LPD8806 LED strip-- code question

by howardb on Sat Mar 30, 2013 8:06 pm

thanks for that information. I can trace this out now.
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