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43 lines
1.5 KiB
43 lines
1.5 KiB
// 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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class Linux::RCInput_AioPRU : public Linux::RCInput |
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{ |
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public: |
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void init(); |
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void _timer_tick(void); |
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private: |
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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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