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- /*
- Copyright 2012 Jun WAKO <[email protected]>
-
- This software is licensed with a Modified BSD License.
- All of this is supposed to be Free Software, Open Source, DFSG-free,
- GPL-compatible, and OK to use in both free and proprietary applications.
- Additions and corrections to this file are welcome.
-
-
- Redistribution and use in source and binary forms, with or without
- modification, are permitted provided that the following conditions are met:
-
- * Redistributions of source code must retain the above copyright
- notice, this list of conditions and the following disclaimer.
-
- * Redistributions in binary form must reproduce the above copyright
- notice, this list of conditions and the following disclaimer in
- the documentation and/or other materials provided with the
- distribution.
-
- * Neither the name of the copyright holders nor the names of
- contributors may be used to endorse or promote products derived
- from this software without specific prior written permission.
-
- THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
- AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
- IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
- ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
- LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
- CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
- SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
- INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
- CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
- ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
- POSSIBILITY OF SUCH DAMAGE.
- */
-
- #include <stdbool.h>
- #include <avr/io.h>
- #include <avr/interrupt.h>
- #include <util/delay.h>
- #include "serial.h"
-
- /*
- * Stupid Inefficient Busy-wait Software Serial
- * is still useful for negative logic signal like Sun protocol not supported by hardware USART.
- */
-
- #define WAIT_US (1000000/SERIAL_BAUD)
-
- void serial_init(void)
- {
- SERIAL_RXD_INIT();
- SERIAL_TXD_INIT();
- }
-
- /* RX ring buffer */
- #define RBUF_SIZE 8
- static uint8_t rbuf[RBUF_SIZE];
- static uint8_t rbuf_head = 0;
- static uint8_t rbuf_tail = 0;
-
- uint8_t serial_recv(void)
- {
- uint8_t data = 0;
- if (rbuf_head == rbuf_tail) {
- return 0;
- }
-
- data = rbuf[rbuf_tail];
- rbuf_tail = (rbuf_tail + 1) % RBUF_SIZE;
- return data;
- }
-
- void serial_send(uint8_t data)
- {
- /* signal state: IDLE: ON, START: OFF, STOP: ON, DATA0: OFF, DATA1: ON */
- /* start bit */
- SERIAL_TXD_OFF();
- _delay_us(WAIT_US);
-
- #ifdef SERIAL_BIT_ORDER_MSB
- uint8_t mask = 0x80;
- #else
- uint8_t mask = 0x01;
- #endif
- while (mask) {
- if (data&mask) { SERIAL_TXD_ON(); } else { SERIAL_TXD_OFF(); }
- _delay_us(WAIT_US);
-
- #ifdef SERIAL_BIT_ORDER_MSB
- mask >>= 1;
- #else
- mask <<= 1;
- #endif
- }
-
- /* stop bit */
- SERIAL_TXD_ON();
- _delay_us(WAIT_US);
- }
-
- /* detect edge of start bit */
- ISR(SERIAL_RXD_VECT)
- {
- SERIAL_RXD_INT_ENTER()
-
- uint8_t data = 0;
- #ifdef SERIAL_BIT_ORDER_MSB
- uint8_t mask = 0x80;
- #else
- uint8_t mask = 0x01;
- #endif
- /* to center of start bit */
- _delay_us(WAIT_US/2);
- do {
- /* to center of next bit */
- _delay_us(WAIT_US);
-
- if (SERIAL_RXD_READ()) {
- data |= mask;
- }
- #ifdef SERIAL_BIT_ORDER_MSB
- mask >>= 1;
- #else
- mask <<= 1;
- #endif
- } while (mask);
- /* to center of stop bit */
- _delay_us(WAIT_US);
-
- uint8_t next = (rbuf_head + 1) % RBUF_SIZE;
- if (next != rbuf_tail) {
- rbuf[rbuf_head] = data;
- rbuf_head = next;
- }
-
- SERIAL_RXD_INT_EXIT();
- }
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