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100 lines
3.4 KiB
100 lines
3.4 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 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); |