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65 lines
2.2 KiB
65 lines
2.2 KiB
/* |
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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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/* |
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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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