mirror of https://github.com/ArduPilot/ardupilot
48 lines
1.6 KiB
C++
48 lines
1.6 KiB
C++
// This program is free software: you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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// This program is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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// You should have received a copy of the GNU General Public License
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// along with this program. If not, see <http://www.gnu.org/licenses/>.
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#pragma once
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/*
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This class implements RCInput on the BeagleBoneBlack with a PRU
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doing the edge detection of the PPM sum input
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*/
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#include "AP_HAL_Linux.h"
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#define RCIN_PRUSS_RAM_BASE 0x4a303000
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// we use 300 ring buffer entries to guarantee that a full 25 byte
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// frame of 12 bits per byte
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namespace Linux {
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class RCInput_AioPRU : public RCInput {
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public:
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void init();
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void _timer_tick(void);
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protected:
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static const uint32_t TICK_PER_US = 200;
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static const uint32_t NUM_RING_ENTRIES = 300;
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// shared ring buffer with the PRU which records pin transitions
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struct ring_buffer {
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volatile uint16_t ring_head; // owned by ARM CPU
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volatile uint16_t ring_tail; // owned by the PRU
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struct {
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volatile uint32_t s1_t; // 5ns per tick
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volatile uint32_t s0_t; // 5ns per tick
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} buffer[NUM_RING_ENTRIES];
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};
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volatile struct ring_buffer *ring_buffer;
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};
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}
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