env var fmon (F_CPU)

1 files changed, 4 insertions, 5 deletions

diff --git a/avr/serial.c b/avr/serial.c
index adbc3c4..d3aeb4e 100644
--- a/avr/serial.c
+++ b/avr/serial.c
@@ -45,15 +45,14 @@ void usart0_setup(unsigned long baud) {
 
 		PRR0 &= ~_BV(PRUSART0);
 		UCSR0B = 0;
+		UCSR0A = 0;
+		UBRR0  = (F_CPU + (baud/2) + 8) / baud / 16 - 1;
+		UCSR0B = _BV(RXCIE0) | _BV(RXEN0) | _BV(TXEN0);
+		UCSR0C = 3 << UCSZ00;
 
 		/* Initialize ring buffers. */
 		ring_init(&rx_ring, rx_ring_buffer, BUFFER_SIZE);
 		ring_init(&tx_ring, tx_ring_buffer, BUFFER_SIZE);
-
-		UCSR0A = 0;
-		UBRR0  = F_CPU / baud / 16 - 1;
-		UCSR0B = _BV(RXCIE0) | _BV(RXEN0) | _BV(TXEN0);
-		UCSR0C = 3 << UCSZ00;
 	};
 }