//---------------------------------------------------------------------
// Program: dual_chaser
//
// Description: 12 LED dual chaser. One led moves from left to right
// while the second LED moves from right to left.
// LEDs and series resistors connected to pins 2 to 13.
//
// Date: 8 April 2016 Author: W.A. Smith
// http://startingelectronics.org
//---------------------------------------------------------------------
// change speed of display here
#define SPEED_MS 100
void setup() {
// set up pins 2 to 13 as outputs
for (int i = 2; i <= 13; i++) {
pinMode(i, OUTPUT);
}
}
uint16_t chase2 = 13; // keeps track of second LED movement
void loop() {
// move first LED from left to right and second from right to left
for (int i = 2; i < 13; i++) {
allLEDsOff();
digitalWrite(i, HIGH); // chaser 1
digitalWrite(chase2, HIGH); // chaser 2
chase2–;
// stop LEDs from appearing to stand still in the middle
if (chase2 != 7) {
delay(SPEED_MS);
}
}
// move first LED from right to left and second LED from left to right
for (int i = 13; i > 2; i–) {
allLEDsOff();
digitalWrite(i, HIGH); // chaser 1
digitalWrite(chase2, HIGH); // chaser 2
chase2++;
// stop LEDs from appearing to stand still in the middle
if (chase2 != 8) {
delay(SPEED_MS);
}
}
}
// function to switch all LEDs off
void allLEDsOff(void)
{
for (int i = 2; i <= 13; i++) {
digitalWrite(i, LOW);
}
}