2012-10-23 22:02:36 -03:00
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/****************************************************************************
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*
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* Copyright (C) 2012 PX4 Development Team. All rights reserved.
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*
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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
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* are met:
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*
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* 1. 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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* 2. 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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* 3. Neither the name PX4 nor the names of its contributors may be
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* used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
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* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
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* 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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****************************************************************************/
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2012-10-24 03:38:45 -03:00
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2012-10-23 22:02:36 -03:00
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/**
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* @file ppm_decode.h
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*
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* PPM input decoder.
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*/
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#pragma once
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#include <drivers/drv_hrt.h>
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/**
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* Maximum number of channels that we will decode.
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*/
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#define PPM_MAX_CHANNELS 12
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2012-11-02 03:42:36 -03:00
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/* PPM input nominal min/max values */
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#define PPM_MIN 1000
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#define PPM_MAX 2000
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#define PPM_MID ((PPM_MIN + PPM_MAX) / 2)
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2012-10-23 22:02:36 -03:00
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__BEGIN_DECLS
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/*
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* PPM decoder state
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*/
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2012-11-02 03:42:36 -03:00
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__EXPORT extern uint16_t ppm_buffer[PPM_MAX_CHANNELS]; /**< decoded PPM channel values */
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2012-10-23 22:02:36 -03:00
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__EXPORT extern unsigned ppm_decoded_channels; /**< count of decoded channels */
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__EXPORT extern hrt_abstime ppm_last_valid_decode; /**< timestamp of the last valid decode */
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/**
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* Initialise the PPM input decoder.
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*
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* @param count_max The maximum value of the counter passed to
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* ppm_input_decode, used to determine how to
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* handle counter wrap.
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*/
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__EXPORT void ppm_input_init(unsigned count_max);
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/**
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* Inform the decoder of an edge on the PPM input.
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*
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* This function can be registered with the HRT as the PPM edge handler.
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*
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* @param reset If set, the edge detector has missed one or
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* more edges and the decoder needs to be reset.
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* @param count A microsecond timestamp corresponding to the
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* edge, in the range 0-count_max. This value
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* is expected to wrap.
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*/
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__EXPORT void ppm_input_decode(bool reset, unsigned count);
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__END_DECLS
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