   Robot.noStroke();
   value_old = value;
   value = batteryVcc();
+  
+  if (value == -1) {
+    // Not got a value yet
+    value = value_old;
+  }
  
   if (value == value_old) {
     // No need to redraw the same value to the screen.

int value_old;

void setup() {
  // initialize the robot
  Robot.begin();
  

  Robot.textSize(2);
  Robot.text("mV", 92, 58); 
  
  return value;
}


int batteryVcc() 
{
