Driving LEDs to Create a Flux Capacitor -- DC to Daylight 08

Ever get the feeling that you may be underdressed and that your wardrobe is somewhat lacking when watching these Element14 videos ? 

Good to see the theory from a previous episode being put into practice in a project.

One minor addition may be to add an external PWM driver to increase the number of LED's from the existing 5 per row so as to be able to increase the control you have over the lighting effects. 

#define A_OFFSET 0
#define B_OFFSET 85
#define C_OFFSET 130
#define MAX_OFFSET C_OFFSET

// helper method

void setLed(uint8_t pin, uint32_t value, uint8_t offset) {
  uint8_t intensity = 0;
  if (value > offset) {
    intensity = (value - offset) > 255 ? 255 : (value - offset);
  }
  analogWrite(pin, intensity);
}

// ...
for (uint32_t counter = 0; counter <= 255 + MAX_OFFSET; counter++) {
  setLed(A, counter, A_OFFSET);
  setLed(B, counter, B_OFFSET);
  setLed(C, counter, C_OFFSET);
} 

If you stick all 5 brightness values into an array then you can loop through that array to drive the LEDs.

You then do 'math' on the array to change the effect.

e.g. for a comet tail type effect you might reduce all the current values of the array by 'x', then set the leading LED value to max.

The values of the array then get written to the LED's at the next update.

You again reduce all the current values of the array by 'x', then turn the next leading LED value on to full.

By doing so you get a fade-out effect following the leading LED.

You may also want to replace your 'blocking' delay() functions with non-blocking code.

If you assign the value returned by millis() to a variable to store the current time (since boot), then later in the code check to see if the time now is greater that the stored time plus an offset value in milliseconds and only if so, then write the contents of the array to the LEDs. Finally update the stored value with the current time.

... but that will make led 2 and 3 flip directly to their offset value, and that's not what you want he?

Changing the helper function should fix that. Thinking ...

One loop should do:

Let's say as example that when LED A is 0, then B is 85, 3 = 130 (each 1/3 offset of each other).

#define A_OFFSET 0

#define B_OFFSET 85

#define C_OFFSET 130

uint8_t counter = 0;



// helper method

void setLed(uint8_t pin, uint8_t value, uint8_t offset {

  uint8_t intensity = ((uint32_t)(value + offset)) > 255 ? 255 : (value + offset);

  analogWrite(pin, intensity);

}




// where you want to make them glow:

for (counter = 0; counter <= 255; counter++) {

  setLed(A, counter, A_OFFSET);

  setLed(B, counter, B_OFFSET);

  setLed(C, counter, C_OFFSET);

}

Hello all! If you have suggestions on how to improve this project, especially related to software let me know here. One of the things I'd like to do is to "power up" three LEDs at the same time so the pulsing looks more natural... meaning three of the LEDs are actively ramping through the PWM values out of phase. I think this would require three nested loops and maybe a state machine. Ideas?