change this
while(Serial.available() == 0);
//readCommand();
//Serial.println(command);
readCommand();
to
if(Serial.available() > 0)
{
readCommand();
}
this
while (!Serial.available())
;
c = Serial.read();
to
while(Serial.available() > 0)
{
c = Serial.read();
if (c == '\r' || c == '\n') {
break;
}
commandBuffer[i] = c;
i++;
}