I changed the 1000 variable to 10000, or 10 seconds. Then, I commented-out the "else" part of the "if" statement (lines 57-66):
if (currentMillis - previousMillis >= interval) {
// save the last time you blinked the LED
previousMillis = currentMillis;
// if the LED is off turn it on and vice-versa:
if (ledState == LOW) {
ledState = HIGH;
//} else {
// ledState = LOW;
}
The LED lights at 10 seconds, and remains high, but this looks like bad code writing.
And, pressing the Uno's reset button initiates a new countdown, but I see three rapid blinks, a very short pause, and then one more split-second blink, before the timing interval starts. What is the purpose of these 4 rapid blinks?