mattallen37:
@Nick Gammon, the compiler complains that some of the variables are undeclared (as if maybe I need to #include something).
Perhaps if you posted your test code, and your error message? This code compiles without errors for me:
void setup ()
{
Serial.begin (115200);
// empty output buffer
Serial.flush ();
// wait for transmit buffer to empty
while ((UCSR0A & _BV (TXC0)) == 0)
{}
}
void loop () {}