139 lines
3.6 KiB
C
139 lines
3.6 KiB
C
/*
|
|
Copyright 2012 Jun WAKO <wakojun@gmail.com>
|
|
|
|
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();
|
|
}
|