134 lines
4.2 KiB
C
134 lines
4.2 KiB
C
/*
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Copyright 2013 Jun WAKO <wakojun@gmail.com>
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This software is licensed with a Modified BSD License.
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All of this is supposed to be Free Software, Open Source, DFSG-free,
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GPL-compatible, and OK to use in both free and proprietary applications.
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Additions and corrections to this file are welcome.
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Redistribution and use in source and binary forms, with or without
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modification, are permitted provided that the following conditions are met:
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* Redistributions of source code must retain the above copyright
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notice, this list of conditions and the following disclaimer.
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* Redistributions in binary form must reproduce the above copyright
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notice, this list of conditions and the following disclaimer in
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the documentation and/or other materials provided with the
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distribution.
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* Neither the name of the copyright holders nor the names of
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contributors may be used to endorse or promote products derived
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from this software without specific prior written permission.
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
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LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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POSSIBILITY OF SUCH DAMAGE.
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*/
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#include <stdbool.h>
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#include <avr/io.h>
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#include <avr/interrupt.h>
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#include "serial.h"
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#ifndef SERIAL_UART_BAUD
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# define SERIAL_UART_BAUD 9600
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#endif
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#define SERIAL_UART_UBRR (F_CPU / (16UL * SERIAL_UART_BAUD) - 1)
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#define SERIAL_UART_TXD_READY (UCSR1A & _BV(UDRE1))
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#define SERIAL_UART_RXD_VECT USART1_RX_vect
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#ifndef SERIAL_UART_INIT_CUSTOM
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# define SERIAL_UART_INIT_CUSTOM \
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/* enable TX */ \
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UCSR1B = _BV(TXEN1); \
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/* 8-bit data */ \
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UCSR1C = _BV(UCSZ11) | _BV(UCSZ10);
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#endif
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#if defined(SERIAL_UART_RTS_LO) && defined(SERIAL_UART_RTS_HI)
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// Buffer state
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// Empty: RBUF_SPACE == RBUF_SIZE(head==tail)
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// Last 1 space: RBUF_SPACE == 2
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// Full: RBUF_SPACE == 1(last cell of rbuf be never used.)
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# define RBUF_SPACE() (rbuf_head < rbuf_tail ? (rbuf_tail - rbuf_head) : (RBUF_SIZE - rbuf_head + rbuf_tail))
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// allow to send
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# define rbuf_check_rts_lo() \
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do { \
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if (RBUF_SPACE() > 2) SERIAL_UART_RTS_LO(); \
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} while (0)
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// prohibit to send
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# define rbuf_check_rts_hi() \
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do { \
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if (RBUF_SPACE() <= 2) SERIAL_UART_RTS_HI(); \
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} while (0)
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#else
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# define rbuf_check_rts_lo()
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# define rbuf_check_rts_hi()
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#endif
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void serial_init(void) {
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do {
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// Set baud rate
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UBRR1L = SERIAL_UART_UBRR;
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UBRR1L = SERIAL_UART_UBRR >> 8;
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SERIAL_UART_INIT_CUSTOM;
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} while (0);
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}
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// RX ring buffer
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#define RBUF_SIZE 256
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static uint8_t rbuf[RBUF_SIZE];
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static uint8_t rbuf_head = 0;
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static uint8_t rbuf_tail = 0;
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uint8_t serial_recv(void) {
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uint8_t data = 0;
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if (rbuf_head == rbuf_tail) {
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return 0;
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}
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data = rbuf[rbuf_tail];
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rbuf_tail = (rbuf_tail + 1) % RBUF_SIZE;
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rbuf_check_rts_lo();
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return data;
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}
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int16_t serial_recv2(void) {
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uint8_t data = 0;
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if (rbuf_head == rbuf_tail) {
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return -1;
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}
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data = rbuf[rbuf_tail];
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rbuf_tail = (rbuf_tail + 1) % RBUF_SIZE;
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rbuf_check_rts_lo();
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return data;
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}
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void serial_send(uint8_t data) {
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while (!SERIAL_UART_TXD_READY)
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;
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SERIAL_UART_DATA = data;
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}
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// USART RX complete interrupt
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ISR(SERIAL_UART_RXD_VECT) {
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uint8_t next = (rbuf_head + 1) % RBUF_SIZE;
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if (next != rbuf_tail) {
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rbuf[rbuf_head] = SERIAL_UART_DATA;
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rbuf_head = next;
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}
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rbuf_check_rts_hi();
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}
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