Knight Rider on an ESP32-C3

// Knight Rider: a dot sweeping back and forth along six LEDs.
//
// One GPIO per lamp, which is the simplest thing that can work and the reason
// it is the first thing anyone builds with more than one LED. GPIO 7, 6, 5 and
// 4 come out next to each other on the DevKitM-1's left header and GPIO 3 and 2
// a little further along, so the array below is the LEDs in the order they sit
// on the breadboard, not in pin order.
//
// The sweep turns round one short of each end, so the two end lamps are lit
// once per pass and the middle ones twice, which is what stops the bounce
// looking like it sticks at the ends.

const int LAMPS[] = {7, 6, 5, 4, 3, 2};
const int COUNT = 6;
const int STEP_MS = 90;

static void show(int lit) {
  for (int i = 0; i < COUNT; i++) {
    digitalWrite(LAMPS[i], i == lit ? HIGH : LOW);
  }
}

void setup() {
  for (int i = 0; i < COUNT; i++) {
    pinMode(LAMPS[i], OUTPUT);
    digitalWrite(LAMPS[i], LOW);
  }
  Serial.begin(115200);
  Serial.println("Mokxi ESP32-C3: six lamps, one dot");
}

void loop() {
  for (int i = 0; i < COUNT; i++) {
    show(i);
    delay(STEP_MS);
  }
  for (int i = COUNT - 2; i > 0; i--) {
    show(i);
    delay(STEP_MS);
  }
}