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85 lines
3.0 KiB
85 lines
3.0 KiB
/**************************************************************************** |
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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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/** |
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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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/* 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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__BEGIN_DECLS |
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/* |
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* PPM decoder state |
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*/ |
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__EXPORT extern uint16_t ppm_buffer[PPM_MAX_CHANNELS]; /**< decoded PPM channel values */ |
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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 |