forked from Archive/PX4-Autopilot
100 lines
3.4 KiB
C
100 lines
3.4 KiB
C
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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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/**
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* @file PPM input decoder.
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*
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* Works in conjunction with the HRT driver, exports a device node
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* and a message queue (if message queues are enabled).
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*
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* Note that the device node supports both blocking and non-blocking
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* opens, but actually never blocks. A nonblocking open will return
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* EWOULDBLOCK if there has not been an update since the last read,
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* while a blocking open will always return the most recent data.
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*/
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#include <sys/ioctl.h>
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#define _PPM_INPUT_BASE 0x7600
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/*
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* Fetch the state of the PPM input detector.
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*/
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#define PPM_INPUT_STATUS _IOC(_PPM_INPUT_BASE, 0)
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typedef enum {
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PPM_STATUS_NO_SIGNAL = 0,
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PPM_STATUS_SIGNAL_CURRENT = 1,
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} ppm_input_status_t;
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/*
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* Fetch the number of channels decoded (only valid when PPM_STATUS_SIGNAL_CURRENT).
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*/
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#define PPM_INPUT_CHANNELS _IOC(_PPM_INPUT_BASE, 1)
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typedef int ppm_input_channel_count_t;
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/*
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* Device node
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*/
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#define PPM_DEVICE_NODE "/dev/ppm_input"
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/*
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* Message queue; if message queues are supported, PPM input data is
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* supplied to the queue when a frame is decoded.
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*/
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#ifndef CONFIG_DISABLE_MQUEUE
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# define PPM_MESSAGE_QUEUE "ppm_input"
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#endif
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/*
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* Private hook from the HRT driver to the PPM decoder.
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*
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* This function is called for every edge of the incoming PPM
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* signal.
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*
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* @param reset If true, the decoder should be reset (e.g.)
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* capture failure was detected.
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* @param count The counter value at which the edge
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* was captured.
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*/
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void ppm_input_decode(bool reset, uint16_t count);
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/*
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* PPM input initialisation function.
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*
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* If message queues are enabled, and mq_name is not NULL, received input
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* is posted to the message queue as an array of 16-bit unsigned channel values.
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*/
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int ppm_input_init(const char *mq_name);
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