int led[]={6,7,8,9,10,11,12,13};
bool upDown=1;
int i=0;
int delayTime=200;
long lastTime=0;
int sw1=2;
int sw2=3;

void setup() 
{                
  for(int i=0; i<=7; i++)
  {
    pinMode(led[i], OUTPUT);
    digitalWrite(led[i],LOW);
  } 
  pinMode(sw1, INPUT_PULLUP);   
  pinMode(sw2, INPUT_PULLUP);  
  Serial.begin(115200);
  i=0;
}


void loop() 
{
  if((digitalRead(sw1)==0)&&(i<254))
  {
    i++;
    out8bit(i);
  }
  
  if((digitalRead(sw2)==0)&&(i>0))
  {
    i--;
    out8bit(i);
  }
  Serial.print("i=");
  Serial.print(i);
  Serial.print(" ,");
  Serial.println(i,BIN);
  delay(100);
}

void out8bit(unsigned char data)
{
  digitalWrite(led[0],data&B00000001);
  digitalWrite(led[1],data&B00000010);
  digitalWrite(led[2],data&B00000100);
  digitalWrite(led[3],data&B00001000);
  digitalWrite(led[4],data&B00010000);
  digitalWrite(led[5],data&B00100000);
  digitalWrite(led[6],data&B01000000);
  digitalWrite(led[7],data&B10000000);
}