It contains the U2X0 bit, which must be cleared to get the desired
bitrate. Some versions of the Arduino bootloader appear to leave it
set.
baud = (F_CPU/16+baud/2)/baud-1;
UBRR0H = baud>>8;
UBRR0L = baud;
baud = (F_CPU/16+baud/2)/baud-1;
UBRR0H = baud>>8;
UBRR0L = baud;
UCSR0C = BIT(UCSZ00) | BIT(UCSZ01); // 8N1
UCSR0B = BIT(RXEN0) | BIT(TXEN0) | BIT(RXCIE0);
}
UCSR0C = BIT(UCSZ00) | BIT(UCSZ01); // 8N1
UCSR0B = BIT(RXEN0) | BIT(TXEN0) | BIT(RXCIE0);
}