ardupilot/libraries/AP_HAL_Linux/RCInput_PRU.h

36 lines
918 B
C++

#pragma once
/*
This class implements RCInput on the BeagleBoneBlack with a PRU
doing the edge detection of the PPM sum input
*/
#include "AP_HAL_Linux.h"
#define RCIN_PRUSS_SHAREDRAM_BASE 0x4a312000
// we use 300 ring buffer entries to guarantee that a full 25 byte
// frame of 12 bits per byte
class Linux::RCInput_PRU : public Linux::RCInput
{
public:
void init();
void _timer_tick(void);
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;
};