mirror of https://github.com/ArduPilot/ardupilot
36 lines
918 B
C++
36 lines
918 B
C++
#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_SHAREDRAM_BASE 0x4a312000
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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_PRU : 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 unsigned int 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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uint16_t pin_value;
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uint16_t delta_t;
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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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// time spent in the low state
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uint16_t _s0_time;
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};
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