I've been looking around for "common cathode vs. common anode" information on LED's, and found that there is a much simpler way of approaching the use of my existing eyephones. This
post on the adafruit forum was pretty insightful.
To that end, I set up a test sketch thus:
/*********************************************************
Sketch: Eyephone Test
Author: Chris Sparnicht - http://low.li
Date: 2011.01.31
License: Creative Commons 2.5 Attrib. & Share Alike
Description: A test for stereo led eye phones.
Notes:
Common Anode Blink Test for existing LED Glasses
Blinks two sets of LED's alternately in loop, using a common anode.
When pins 5 and 6 are set to LOW, they emit light (on).
When each pin is set to HIGH the no longer emit light (off).
*********************************************************/
// Some variables:
int intensity[]={255, 127, 63, 31, 15};
int rintensity[]={15, 31, 63, 127, 255};
/*********************************************************
Setup defines LED outputs.
*********************************************************/
void setup() {
// initialize the digital pin as an output.
// The LED's anodes :
pinMode(5, OUTPUT); // LED's on right side
pinMode(6, OUTPUT); // LED's on left side
}
/*********************************************************
Main function - blink the LED's continuously in a loop
*********************************************************/
void loop() {
for (int i = 0; i < 5; i++) {
// Two blinks on one side to confirm which pin is right or left.
// Do this five times.
digitalWrite(5, HIGH); // Common Anode: Turn LED off.
digitalWrite(6, LOW); // Common Anode: Turn LED on.
delay(250); // wait for a second
digitalWrite(5, LOW); // Common Anode: Turn LED off.
digitalWrite(6, LOW); // Common Anode: Turn LED on.
delay(250); // wait for a second
digitalWrite(5, HIGH); // Common Anode: Turn LED off.
digitalWrite(6, LOW); // Common Anode: Turn LED on.
delay(250); // wait for a second
digitalWrite(5, LOW); // Common Anode: Turn LED off.
digitalWrite(6, LOW); // Common Anode: Turn LED on.
delay(250); // wait for a second
// Single blink on second in order to verify both sides function.
digitalWrite(5, LOW); // Common Anode: Turn LED on.
digitalWrite(6, HIGH); // Common Anode: Turn LED off.
delay(1000); // wait for a second
}
// Now do some PWM to show it works in reverse for PWM too.
for (int i = 0; i < 5; i++) {
for (int i = 0; i < 5; i++) { // over the course of a second
analogWrite(5, intensity[i]); // Right side: dim to bright
analogWrite(6, 0); //
delay(200);
}
for (int i = 0; i < 5; i++) { // over the course of a second
analogWrite(5, 0); //
analogWrite(6, rintensity[i]); // Left Side: bright to dim
delay(200);
}
}
}
I set up a double blink for the LED's on the right side just to confirm that the pin I'd specified was on the correct side. The fact that the left side LED's emit light during the double blink on the right side confirms that LOW means "On" and HIGH means "Off" with a common anode situation. Likewise, the analogWrite values are reverse as well. It looks like no transistors are necessary for this part of the programming. I may just need to inverse pin values in the sketch. Cool!
This is how the test is laid out on a bred board:
I can't tell whether I'm learning electronics incidentally to programming or vice versa. Either way, this is excellent fun.
The next thing to tackle is a better method for the earphones.
