#include <TimerOne.h>

volatile int current = 0;
volatile bool direction = false;

void setup() {
  Serial.begin(115200);
  Timer1.initialize(100000);
  Timer1.attachInterrupt(next);
  attachInterrupt(digitalPinToInterrupt(2), change, RISING);
  for(int i = 0; i < 9; i++){
    pinMode(i+3, OUTPUT);
    digitalWrite(i+3, LOW);
  }
}

void next(){
  digitalWrite(current + 3, LOW);
  if(direction){
    if(++current > 8) current = 0;
  }
  else{
    if(--current < 0) current = 9;
  }
  digitalWrite(current + 3, HIGH);
}

void change(){
  direction = !direction;
  Serial.println("Changed direction");
}

void loop() {

}