123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129 |
- // 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;
- }
- }
|