avr/avr_demo
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Reset ringbuffer when calling uart_init()

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This commit is contained in:
Mika Tuupola 2011-10-09 01:42:27 +03:00
parent 55056f94f0
commit 91025af29e
2 changed files with 13 additions and 1 deletions
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3
hello_uart_async/uart.h
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@ -3,6 +3,9 @@ int uart_getchar(FILE *stream);
void uart_init(void); void uart_init(void);
struct rx_ring;
struct tx_ring;
/* http://www.ermicro.com/blog/?p=325 */ /* http://www.ermicro.com/blog/?p=325 */
FILE uart_output = FDEV_SETUP_STREAM(uart_putchar, NULL, _FDEV_SETUP_WRITE); FILE uart_output = FDEV_SETUP_STREAM(uart_putchar, NULL, _FDEV_SETUP_WRITE);

11
hello_uart_async/uart_async.c
View File

@ -1,3 +1,5 @@
/* Based on Atmel Application Note AVR 306 */
#include <avr/io.h> #include <avr/io.h>
#include <avr/interrupt.h> #include <avr/interrupt.h>
#include <stdio.h> #include <stdio.h>
@ -33,6 +35,13 @@ static struct rx_ring rx_buffer;
/* http://www.cs.mun.ca/~rod/Winter2007/4723/notes/serial/serial.html */ /* http://www.cs.mun.ca/~rod/Winter2007/4723/notes/serial/serial.html */
void uart_init(void) { void uart_init(void) {
tx_buffer.start = 0;
tx_buffer.end = 0;
rx_buffer.start = 0;
rx_buffer.end = 0;
UBRR0H = UBRRH_VALUE; UBRR0H = UBRRH_VALUE;
UBRR0L = UBRRL_VALUE; UBRR0L = UBRRL_VALUE;
@ -80,7 +89,7 @@ ISR(USART_RX_vect) {
ISR(USART_UDRE_vect){ ISR(USART_UDRE_vect){
int read_pointer = (tx_buffer.start + 1) % UART_TX_BUFFER_SIZE; int read_pointer = (tx_buffer.start + 1) % UART_TX_BUFFER_SIZE;
/* Transit next byte if data available in ringbuffer. */ /* Transmit next byte if data available in ringbuffer. */
if (read_pointer != tx_buffer.end) { if (read_pointer != tx_buffer.end) {
UDR0 = tx_buffer.buffer[read_pointer]; UDR0 = tx_buffer.buffer[read_pointer];
tx_buffer.start = read_pointer; tx_buffer.start = read_pointer;