Use TX end IRQ instead of busy wait

[openparking.git] / firmware / rs485.c

diff --git a/firmware/rs485.c b/firmware/rs485.c
index 6d16a2af05840de11d0808bfe1d63c0ded2e5100..7aec92c8e54a4abf1f31691b411e44a5aac4a167 100644 (file)
--- a/firmware/rs485.c
+++ b/firmware/rs485.c
@@ -34,7 +34,6 @@ static volatile char rxbuf[BUFSIZE], txbuf[BUFSIZE];
 
 #define UART_BAUD      9600
 #define UBRR_VAL        ((F_CPU + 8UL * UART_BAUD) / (16UL*UART_BAUD) - 1)
-#define wait_one_byte()        _delay_us(10*1000000/UART_BAUD)
 
 void rs485_init()
 {
@@ -99,13 +98,18 @@ ISR(USART_RX_vect)
        sei();
 }
 
+ISR(USART_TX_vect)
+{
+       UCSR0B &= ~_BV(TXCIE0); // disable further IRQs
+       ctl_pin_off();
+}
+
 ISR(USART_UDRE_vect)
 {
        cli();
        if (tx_head == tx_tail) {
+               UCSR0B |= _BV(TXCIE0); // enable xmit complete irq
                UCSR0B &= ~_BV(UDRIE0);
-               wait_one_byte();
-               ctl_pin_off();
        } else {
                UDR0 = txbuf[tx_tail];
                tx_tail = bufptr_inc(tx_tail);