Drain serial port before changing speed

[fw/altos] / src / ao_serial.c

diff --git a/src/ao_serial.c b/src/ao_serial.c
index f2f5e69736e6540f07572d90b9ba45a163337059..4155e776934ac59f196e67642aa23d462d011025 100644 (file)
--- a/src/ao_serial.c
+++ b/src/ao_serial.c
@@ -60,7 +60,7 @@ ao_serial_getchar(void) __critical
                ao_sleep(&ao_usart1_rx_fifo);
        ao_fifo_remove(ao_usart1_rx_fifo, c);
        if (serial_echo) {
-               printf("%02x\n", (uint8_t) c);
+               printf("%02x\n", ((int) c) & 0xff);
                flush();
        }
        return c;
@@ -75,6 +75,13 @@ ao_serial_putchar(char c) __critical
        ao_serial_tx1_start();
 }
 
+static void
+ao_serial_drain(void) __critical
+{
+       while (!ao_fifo_empty(ao_usart1_tx_fifo))
+               ao_sleep(&ao_usart1_tx_fifo);
+}
+
 static void
 send_serial(void)
 {
@@ -115,6 +122,9 @@ static const struct {
 void
 ao_serial_set_speed(uint8_t speed)
 {
+       ao_serial_drain();
+       if (speed > AO_SERIAL_SPEED_57600)
+               return;
        U1BAUD = ao_serial_speeds[speed].baud;
        U1GCR = ao_serial_speeds[speed].gcr;
 }