"Waking up" waveform

Using Arduino LEDs and Multiplexing
1

I'm looking for a waveform to drive the brightness of leds so the appearance is that the device with the leds is "waking up". I've done a lot of searching and run off on a lot of unproductive tangents. I have to think that many before me have used creative waveforms in a variety of projects. Any ideas on what to search on ?

I'm thinking of a waveform that has a steep, probably linear rise to get to max brightness and then some sort of rolloff or decay as the brightness diminishes.

This is for a Stars wars like light saber that I have built, programmed and is complete except for this part. I would like for it to "wake up" as a prelude to the light show.

2

Here ya go buddy. Got this from "Getting Started with Arduino" Book. Have fun! hopefully it'll help... :slight_smile:

// Copy and paste this example into an empty Arduino sketch

#define LED 9 // the pin for the LED
int i = 0; // We’ll use this to count up and down

void setup() {
pinMode(LED, OUTPUT); // tell Arduino LED is an output
}

void loop(){

for (i = 0; i < 255; i++) { // loop from 0 to 254 (fade in)
analogWrite(LED, i); // set the LED brightness

delay(10); // Wait 10ms because analogWrite
// is instantaneous and we would
// not see any change
}

for (i = 255; i > 0; i--) { // loop from 255 to 1 (fade out)

analogWrite(LED, i); // set the LED brightness
delay(10); // Wait 10ms
}

}

3

Thanks, but I'm way beyond that. I've looked at sine, ramp, exponential and combinations and still haven't found what I want. I have and I suspect many others as well seen what I want in Disney and other children's clips.

Thanks for the thought though.

4

So why not just write that in setup?
Take ebird97s code, increase the count by 10 instead of 1 so it goes up quicker, than change direction and ramp it down by increments of 1 or 2 down to whatever your pre-show level is.