sbus.h
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/****************************************************************************
*
* Copyright (c) 2012-2015 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 sbus.h
*
* RC protocol definition for S.BUS
*
* @author Lorenz Meier <lorenz@px4.io>
*/
#pragma once
#include <stdint.h>
#include <stdbool.h>
__BEGIN_DECLS
#define SBUS_FRAME_SIZE 25
#define SBUS_BUFFER_SIZE (SBUS_FRAME_SIZE + SBUS_FRAME_SIZE / 2)
typedef uint8_t sbus_frame_t[SBUS_FRAME_SIZE + (SBUS_FRAME_SIZE / 2)];
__EXPORT int sbus_init(const char *device, bool singlewire);
/**
* Parse serial bytes on the S.BUS bus
*
* The S.bus protocol doesn't provide reliable framing,
* so we detect frame boundaries by the inter-frame delay.
*
* The minimum frame spacing is 7ms; with 25 bytes at 100000bps
* frame transmission time is 3ms.
*
* If an interval of more than 4ms (7 ms frame spacing plus margin)
* passes between calls, the first byte we read will be the first
* byte of a frame.
*
* In the case where byte(s) are dropped from a frame, this also
* provides a degree of protection. Of course, it would be better
* if we didn't drop bytes...
*/
__EXPORT int sbus_config(int sbus_fd, bool singlewire);
__EXPORT bool sbus_input(int sbus_fd, uint16_t *values, uint16_t *num_values, bool *sbus_failsafe,
bool *sbus_frame_drop,
uint16_t max_channels);
__EXPORT bool sbus_parse(uint64_t now, uint8_t *frame, unsigned len, uint16_t *values,
uint16_t *num_values, bool *sbus_failsafe, bool *sbus_frame_drop, unsigned *frame_drops, uint16_t max_channels);
__EXPORT void sbus1_output(int sbus_fd, uint16_t *values, uint16_t num_values);
__EXPORT void sbus2_output(int sbus_fd, uint16_t *values, uint16_t num_values);
__EXPORT void sbus1_set_output_rate_hz(uint16_t rate_hz);
/**
* The number of incomplete frames we encountered
*/
__EXPORT unsigned sbus_dropped_frames(void);
__END_DECLS