#define DIR    19
#define STEP   20
#define PUSH   28
#define PUS    27

void setup() {
 pinMode(DIR, OUTPUT);
 pinMode(STEP, OUTPUT);
 pinMode(PUSH, INPUT_PULLUP);
 pinMode(PUS, INPUT_PULLUP);
}

void loop() {
  //-
  digitalWrite(DIR, LOW);
  if(digitalRead(PUSH) == 0)
  digitalWrite(STEP, HIGH);
  else 
    digitalWrite(STEP, LOW);
  delay(1); 
  //+
   digitalWrite(DIR, HIGH);
  if(digitalRead(PUS) == 0)
  digitalWrite(STEP, HIGH);
  else 
    digitalWrite(STEP, LOW);
  delay(1); 
}