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/****************************************************************************
*
* Copyright (C) 2012,2013 PX4 Development Team. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. 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.
* 3. Neither the name PX4 nor the names of its 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.
*
****************************************************************************/
/**
* @file serial.c
*
* Serial communication for the PX4IO module.
*/
#include <stdint.h>
#include <unistd.h>
#include <termios.h>
#include <fcntl.h>
#include <string.h>
#include <nuttx/arch.h>
#include <arch/board/board.h>
#include <systemlib/hx_stream.h>
//#define DEBUG
#include "px4io.h"
static uint8_t tx_buf[66]; /* XXX hardcoded magic number */
static hx_stream_t if_stream;
static void serial_callback(void *arg, const void *data, unsigned length);
void
interface_init(void)
{
int fd = open("/dev/ttyS1", O_RDWR, O_NONBLOCK);
if (fd < 0) {
debug("serial fail");
return;
}
/* configure serial port - XXX increase port speed? */
struct termios t;
tcgetattr(fd, &t);
cfsetspeed(&t, 115200);
t.c_cflag &= ~(CSTOPB | PARENB);
tcsetattr(fd, TCSANOW, &t);
/* allocate the HX stream we'll use for communication */
if_stream = hx_stream_init(fd, serial_callback, NULL);
/* XXX add stream stats counters? */
debug("serial init");
}
void
interface_tick()
{
/* process incoming bytes */
hx_stream_rx(if_stream);
}
static void
serial_callback(void *arg, const void *data, unsigned length)
{
const uint8_t *message = (const uint8_t *)data;
/* malformed frame, ignore it */
if (length < 2)
return;
/* it's a write operation, pass it to the register API */
if (message[0] & PX4IO_PAGE_WRITE) {
registers_set(message[0] & ~PX4IO_PAGE_WRITE, message[1],
(const uint16_t *)&message[2],
(length - 2) / 2);
return;
}
/* it's a read - must contain length byte */
if (length != 3)
return;
uint16_t *registers;
unsigned count;
tx_buf[0] = message[0];
tx_buf[1] = message[1];
/* get registers for response, send an empty reply on error */
if (registers_get(message[0], message[1], ®isters, &count) < 0)
count = 0;
/* fill buffer with message, limited by length */
#define TX_MAX ((sizeof(tx_buf) - 2) / 2)
if (count > TX_MAX)
count = TX_MAX;
if (count > message[2])
count = message[2];
memcpy(&tx_buf[2], registers, count * 2);
/* try to send the message */
hx_stream_send(if_stream, tx_buf, count * 2 + 2);
}
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