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This was part of a student lecture in the computation class. We discussed PWM and applying it to multiple LED’s and tri-color LED’s. Here’s pcitures and code for the 2 circuits I built and presented in class.

Multiple LED’s with PWM

Code:

int value = 0; // variable to keep the actual value<br /> int pins[] = {9, 10, 11}; // light connected to digital pin 9<br /> int numPins = 3;</p> <p>void setup()<br /> {<br /> // nothing for setup<br /> }</p> <p>void loop()<br /> {<br /> int i;</p> <p>for (i=0; i < numPins; i++)<br /> {<br /> for(value = 0 ; value <= 255; value+=5) // fade in (from min to max)<br /> {<br /> analogWrite(pins[i], value); // sets the value (range from 0 to 255)<br /> delay(30); // waits for 30 milli seconds to see the dimming effect<br /> }<br /> }<br /> int j;<br /> for (j=numPins-1; j >= 0; j–)<br /> {<br /> for(value = 255; value >=0; value-=5) // fade out (from max to min)<br /> {<br /> analogWrite(pins[j], value);<br /> delay(30);<br /> }<br /> }<br /> }</p> <p>

Tri-Color LED

Code:

// light connected to digital pin 9, 10, 11<br /> int pins[] = {9, 10, 11};</p> <p>void setup()<br /> {<br /> // nothing for setup<br /> }</p> <p>void loop()<br /> {<br /> // variable to keep the actual value<br /> int value = 0;</p> <p>//variables to check if fade in for a color is complete<br /> int fadedIn1 = 0;<br /> int fadedIn2 = 0;<br /> int fadedIn3 = 0;</p> <p>//variables to check if fade out for a color is complete<br /> int fadedOut1 = 0;<br /> int fadedOut2 = 0;<br /> int fadedOut3 = 0;</p> <p>//fade in blue<br /> if (fadedIn1 != 1){<br /> for(value = 255; value >=0; value-=5)<br /> {<br /> analogWrite(pins[1], value);<br /> delay(60);<br /> fadedIn1 = 1;<br /> }<br /> }</p> <p>//fade in green<br /> if (fadedIn2 != 1){<br /> for(value = 255; value >=0; value-=5)<br /> {<br /> analogWrite(pins[0], value);<br /> delay(60);<br /> fadedIn2 = 1;<br /> }<br /> }</p> <p>//fade in red<br /> if (fadedIn3 != 1){<br /> for(value = 255; value >=0; value-=5)<br /> {<br /> analogWrite(pins[2], value);<br /> delay(60);<br /> fadedIn3 = 1;<br /> }<br /> }</p> <p>//fade out red<br /> if (fadedOut1 != 1){<br /> for(value = 0; value <=255; value+=5)<br /> {<br /> analogWrite(pins[2], value);<br /> delay(60);<br /> fadedOut1 = 1;<br /> }<br /> }</p> <p>//fade out green<br /> if (fadedOut2 != 1){<br /> for(value = 0; value <=255; value+=5)<br /> {<br /> analogWrite(pins[0], value);<br /> delay(60);<br /> fadedOut2 = 1;<br /> }<br /> }</p> <p>//fade out blue<br /> if (fadedOut3 != 1){<br /> for(value = 0; value <=255; value+=5)<br /> {<br /> analogWrite(pins[1], value);<br /> delay(60);<br /> fadedOut3 = 1;<br /> }<br /> }</p> <p>}</p> <p>

Tagged as arduino, breadboard, computation, LED + Categorized as @Parsons, Spring09, Major Studio: Computation, @Parsons, Spring09