130 line
3.5 KiB
C
130 line
3.5 KiB
C
// TODO: Teensy support(ATMega32u4/AT90USB128)
|
|
// Fixed for Arduino Duemilanove ATmega168p by Jun Wako
|
|
/* UART Example for Teensy USB Development Board
|
|
* http://www.pjrc.com/teensy/
|
|
* Copyright (c) 2009 PJRC.COM, LLC
|
|
*
|
|
* Permission is hereby granted, free of charge, to any person obtaining a copy
|
|
* of this software and associated documentation files (the "Software"), to deal
|
|
* in the Software without restriction, including without limitation the rights
|
|
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
|
|
* copies of the Software, and to permit persons to whom the Software is
|
|
* furnished to do so, subject to the following conditions:
|
|
*
|
|
* The above copyright notice and this permission notice shall be included in
|
|
* all copies or substantial portions of the Software.
|
|
*
|
|
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
|
|
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
|
|
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
|
|
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
|
|
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
|
|
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
|
|
* THE SOFTWARE.
|
|
*/
|
|
|
|
// Version 1.0: Initial Release
|
|
// Version 1.1: Add support for Teensy 2.0, minor optimizations
|
|
|
|
|
|
#include <avr/io.h>
|
|
#include <avr/interrupt.h>
|
|
|
|
#include "uart.h"
|
|
|
|
// These buffers may be any size from 2 to 256 bytes.
|
|
#define RX_BUFFER_SIZE 64
|
|
#define TX_BUFFER_SIZE 40
|
|
|
|
static volatile uint8_t tx_buffer[TX_BUFFER_SIZE];
|
|
static volatile uint8_t tx_buffer_head;
|
|
static volatile uint8_t tx_buffer_tail;
|
|
static volatile uint8_t rx_buffer[RX_BUFFER_SIZE];
|
|
static volatile uint8_t rx_buffer_head;
|
|
static volatile uint8_t rx_buffer_tail;
|
|
|
|
// Initialize the UART
|
|
void uart_init(uint32_t baud)
|
|
{
|
|
cli();
|
|
UBRR0 = (F_CPU / 4 / baud - 1) / 2;
|
|
UCSR0A = (1<<U2X0);
|
|
UCSR0B = (1<<RXEN0) | (1<<TXEN0) | (1<<RXCIE0);
|
|
UCSR0C = (1<<UCSZ01) | (1<<UCSZ00);
|
|
tx_buffer_head = tx_buffer_tail = 0;
|
|
rx_buffer_head = rx_buffer_tail = 0;
|
|
sei();
|
|
}
|
|
|
|
// Transmit a byte
|
|
void uart_putchar(uint8_t c)
|
|
{
|
|
uint8_t i;
|
|
|
|
i = tx_buffer_head + 1;
|
|
if (i >= TX_BUFFER_SIZE) i = 0;
|
|
while (tx_buffer_tail == i) ; // wait until space in buffer
|
|
//cli();
|
|
tx_buffer[i] = c;
|
|
tx_buffer_head = i;
|
|
UCSR0B = (1<<RXEN0) | (1<<TXEN0) | (1<<RXCIE0) | (1<<UDRIE0);
|
|
//sei();
|
|
}
|
|
|
|
// Receive a byte
|
|
uint8_t uart_getchar(void)
|
|
{
|
|
uint8_t c, i;
|
|
|
|
while (rx_buffer_head == rx_buffer_tail) ; // wait for character
|
|
i = rx_buffer_tail + 1;
|
|
if (i >= RX_BUFFER_SIZE) i = 0;
|
|
c = rx_buffer[i];
|
|
rx_buffer_tail = i;
|
|
return c;
|
|
}
|
|
|
|
// Return the number of bytes waiting in the receive buffer.
|
|
// Call this before uart_getchar() to check if it will need
|
|
// to wait for a byte to arrive.
|
|
uint8_t uart_available(void)
|
|
{
|
|
uint8_t head, tail;
|
|
|
|
head = rx_buffer_head;
|
|
tail = rx_buffer_tail;
|
|
if (head >= tail) return head - tail;
|
|
return RX_BUFFER_SIZE + head - tail;
|
|
}
|
|
|
|
// Transmit Interrupt
|
|
ISR(USART_UDRE_vect)
|
|
{
|
|
uint8_t i;
|
|
|
|
if (tx_buffer_head == tx_buffer_tail) {
|
|
// buffer is empty, disable transmit interrupt
|
|
UCSR0B = (1<<RXEN0) | (1<<TXEN0) | (1<<RXCIE0);
|
|
} else {
|
|
i = tx_buffer_tail + 1;
|
|
if (i >= TX_BUFFER_SIZE) i = 0;
|
|
UDR0 = tx_buffer[i];
|
|
tx_buffer_tail = i;
|
|
}
|
|
}
|
|
|
|
// Receive Interrupt
|
|
ISR(USART_RX_vect)
|
|
{
|
|
uint8_t c, i;
|
|
|
|
c = UDR0;
|
|
i = rx_buffer_head + 1;
|
|
if (i >= RX_BUFFER_SIZE) i = 0;
|
|
if (i != rx_buffer_tail) {
|
|
rx_buffer[i] = c;
|
|
rx_buffer_head = i;
|
|
}
|
|
}
|
|
|