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- #pragma once
- /*
- This class implements RCInput on the BeagleBoneBlack with a PRU
- doing the edge detection of the PPM sum input
- */
- #include "RCInput.h"
- // we use 300 ring buffer entries to guarantee that a full 25 byte
- // frame of 12 bits per byte
- namespace Linux {
- class RCInput_PRU : public RCInput {
- public:
- void init() override;
- void _timer_tick(void) override;
- private:
- static const unsigned int NUM_RING_ENTRIES=300;
- // shared ring buffer with the PRU which records pin transitions
- struct ring_buffer {
- volatile uint16_t ring_head; // owned by ARM CPU
- volatile uint16_t ring_tail; // owned by the PRU
- struct {
- uint16_t pin_value;
- uint16_t delta_t;
- } buffer[NUM_RING_ENTRIES];
- };
- volatile struct ring_buffer *ring_buffer;
- // time spent in the low state
- uint16_t _s0_time;
- };
- }
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