mirror of https://github.com/ArduPilot/ardupilot
70 lines
2.3 KiB
C++
70 lines
2.3 KiB
C++
/*
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* This file is free software: you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by the
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* Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This file is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
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* See the GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program. If not, see <http://www.gnu.org/licenses/>.
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*
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* Code by Andrew Tridgell and Siddharth Bharat Purohit
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*/
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#include "AP_RCProtocol_PPMSum.h"
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#if AP_RCPROTOCOL_PPMSUM_ENABLED
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/*
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process a PPM-sum pulse of the given width
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*/
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void AP_RCProtocol_PPMSum::process_pulse(uint32_t width_s0, uint32_t width_s1)
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{
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if (width_s0 == 0 || width_s1 == 0) {
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//invalid data: reset frame
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ppm_state._channel_counter = -1;
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return;
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}
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uint32_t width_usec = width_s0 + width_s1;
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if (width_usec >= 2700) {
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// a long pulse indicates the end of a frame. Reset the
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// channel counter so next pulse is channel 0
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if (ppm_state._channel_counter >= MIN_RCIN_CHANNELS) {
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add_input(ppm_state._channel_counter, ppm_state._pulse_capt, false);
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}
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ppm_state._channel_counter = 0;
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return;
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}
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if (ppm_state._channel_counter == -1) {
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// we are not synchronised
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return;
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}
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/*
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we limit inputs to between 700usec and 2300usec. This allows us
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to decode SBUS on the same pin, as SBUS will have a maximum
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pulse width of 100usec
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*/
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if (width_usec > 700 && width_usec < 2300) {
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// take a reading for the current channel
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// buffer these
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ppm_state._pulse_capt[ppm_state._channel_counter] = width_usec;
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// move to next channel
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ppm_state._channel_counter++;
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}
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// if we have reached the maximum supported channels then
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// mark as unsynchronised, so we wait for a wide pulse
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if (ppm_state._channel_counter >= MAX_RCIN_CHANNELS) {
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add_input(ppm_state._channel_counter, ppm_state._pulse_capt, false);
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ppm_state._channel_counter = -1;
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}
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}
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#endif // AP_RCPROTOCOL_PPMSUM_ENABLED
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