156 lines
3.3 KiB
C
156 lines
3.3 KiB
C
/*
|
|
* Copyright 2011 Mika Tuupola
|
|
*
|
|
* Licensed under the MIT license:
|
|
* http://www.opensource.org/licenses/mit-license.php
|
|
*
|
|
*/
|
|
|
|
/* Based on Atmel Application Note AVR 306 */
|
|
|
|
#include <avr/io.h>
|
|
#include <avr/interrupt.h>
|
|
#include <stdio.h>
|
|
|
|
#ifndef BAUD
|
|
#define BAUD 9600
|
|
#endif
|
|
#include <util/setbaud.h>
|
|
|
|
#ifndef UART_RX_BUFFER_SIZE
|
|
#define UART_RX_BUFFER_SIZE 64
|
|
#endif
|
|
|
|
#ifndef UART_TX_BUFFER_SIZE
|
|
#define UART_TX_BUFFER_SIZE 64
|
|
#endif
|
|
|
|
#if defined (UBRR0H)
|
|
|
|
#warning Using UART0
|
|
#define UBRRxH UBRR0H
|
|
#define UBRRxL UBRR0L
|
|
#define UCSRxA UCSR0A
|
|
#define U2Xx U2X0
|
|
#define UCSRxC UCSR0C
|
|
#define UCSZx1 UCSZ01
|
|
#define UCSZx0 UCSZ00
|
|
#define UCSRxB UCSR0B
|
|
#define RXENx RXEN0
|
|
#define TXENx TXEN0
|
|
#define UDREx UDRE0
|
|
#define RXCx RXC0
|
|
#define UDRx UDR0
|
|
#define UDRIEx UDRIE0
|
|
|
|
#define USARTx_RX_vect USART_RX_vect
|
|
#define USARTx_UDRE_vect USART_UDRE_vect
|
|
#elif defined (UBRR1H)
|
|
|
|
#warning Using UART1
|
|
#define UBRRxH UBRR1H
|
|
#define UBRRxL UBRR1L
|
|
#define UCSRxA UCSR1A
|
|
#define U2Xx U2X1
|
|
#define UCSRxC UCSR1C
|
|
#define UCSZx1 UCSZ11
|
|
#define UCSZx0 UCSZ10
|
|
#define UCSRxB UCSR1B
|
|
#define RXENx RXEN1
|
|
#define TXENx TXEN1
|
|
#define UDREx UDRE1
|
|
#define RXCx RXC1
|
|
#define UDRx UDR1
|
|
#define UDRIEx UDRIE1
|
|
|
|
#define USARTx_RX_vect USART1_RX_vect
|
|
#define USARTx_UDRE_vect USART1_UDRE_vect
|
|
|
|
#else
|
|
#error No UART?
|
|
#endif
|
|
|
|
struct tx_ring {
|
|
int buffer[UART_TX_BUFFER_SIZE];
|
|
int start;
|
|
int end;
|
|
};
|
|
|
|
struct rx_ring {
|
|
int buffer[UART_RX_BUFFER_SIZE];
|
|
int start;
|
|
int end;
|
|
};
|
|
|
|
static struct tx_ring tx_buffer;
|
|
static struct rx_ring rx_buffer;
|
|
|
|
/* http://www.cs.mun.ca/~rod/Winter2007/4723/notes/serial/serial.html */
|
|
|
|
void uart_init(void) {
|
|
|
|
tx_buffer.start = 0;
|
|
tx_buffer.end = 0;
|
|
|
|
rx_buffer.start = 0;
|
|
rx_buffer.end = 0;
|
|
|
|
UBRRxH = UBRRH_VALUE;
|
|
UBRRxL = UBRRL_VALUE;
|
|
|
|
UCSRxC = _BV(UCSZx1) | _BV(UCSZx0); /* 8-bit data */
|
|
UCSRxB = _BV(RXENx) | _BV(TXENx); /* Enable RX and TX */
|
|
|
|
sei();
|
|
}
|
|
|
|
int uart_putchar(char c, FILE *stream) {
|
|
if (c == '\n') {
|
|
uart_putchar('\r', stream);
|
|
}
|
|
|
|
int write_pointer = (tx_buffer.end + 1) % UART_TX_BUFFER_SIZE;
|
|
|
|
if (write_pointer != tx_buffer.start){
|
|
tx_buffer.buffer[tx_buffer.end] = c;
|
|
tx_buffer.end = write_pointer;
|
|
|
|
/* Data available. Enable the transmit interrupt for serial port 0. */
|
|
UCSRxB |= _BV(UDRIEx);
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
int uart_getchar(FILE *stream) {
|
|
int read_pointer = (rx_buffer.start + 1) % UART_RX_BUFFER_SIZE;
|
|
|
|
rx_buffer.start = read_pointer;
|
|
return rx_buffer.buffer[read_pointer];
|
|
}
|
|
|
|
ISR(USARTx_RX_vect) {
|
|
int write_pointer = (rx_buffer.end + 1) % UART_RX_BUFFER_SIZE;
|
|
|
|
/* Add next byte to ringbuffer if it has space available. */
|
|
if (write_pointer != rx_buffer.start){
|
|
rx_buffer.buffer[rx_buffer.end] = UDRx;
|
|
rx_buffer.end = write_pointer;
|
|
}
|
|
}
|
|
|
|
ISR(USARTx_UDRE_vect){
|
|
int read_pointer = (tx_buffer.start + 1) % UART_TX_BUFFER_SIZE;
|
|
|
|
/* Transmit next byte if data available in ringbuffer. */
|
|
if (read_pointer != tx_buffer.end) {
|
|
UDRx = tx_buffer.buffer[read_pointer];
|
|
tx_buffer.start = read_pointer;
|
|
} else {
|
|
/* Nothing to send. Disable the transmit interrupt for serial port x. */
|
|
UCSRxB &= ~_BV(UDRIEx);
|
|
}
|
|
}
|
|
|
|
|