ardupilot/libraries/AP_HAL/RCInput.h

#pragma once

#include "AP_HAL_Namespace.h"

#define RC_INPUT_MIN_PULSEWIDTH 900
#define RC_INPUT_MAX_PULSEWIDTH 2100

class AP_HAL::RCInput {
public:
    /**
     * Call init from the platform hal instance init, so that both the type of
     * the RCInput implementation and init argument (e.g. ISRRegistry) are
     * known to the programmer. (It's too difficult to describe this dependency
     * in the C++ type system.)
     */
    virtual void init() = 0;
    virtual void teardown() {};

    /**
     * Return true if there has been new input since the last call to new_input()
     */
    virtual bool new_input(void) = 0;

    /**
     * Return the number of valid channels in the last read
     */
    virtual uint8_t  num_channels() = 0;

    /* Read a single channel at a time */
    virtual uint16_t read(uint8_t ch) = 0;

    /* Read an array of channels, return the valid count */
    virtual uint8_t read(uint16_t* periods, uint8_t len) = 0;

    /* get receiver based RSSI if available. -1 for unknown, 0 for no link, 255 for maximum link */
    virtual int16_t get_rssi(void) { return -1; }
    virtual int16_t get_rx_link_quality(void) { return -1; }
    /* Return string describing method RC input protocol */
    virtual const char *protocol() const = 0;

    /**
     * Overrides: these are really grody and don't belong here but we need
     * them at the moment to make the port work.
     * case v of:
     *  v == -1 -> no change to this channel
     *  v == 0  -> do not override this channel
     *  v > 0   -> set v as override.
     */

    /* execute receiver bind */
    virtual bool rc_bind(int dsmMode) { return false; }

    /* enable or disable pulse input for RC input. This is used to
       reduce load when we are decoding R/C via a UART */
    virtual void pulse_input_enable(bool enable) { }
};