RHGenericDriver.h

// RHGenericDriver.h
// Author: Mike McCauley (mikem@airspayce.com)
// Copyright (C) 2014 Mike McCauley
// $Id: RHGenericDriver.h,v 1.24 2020/04/09 23:40:34 mikem Exp $

#ifndef RHGenericDriver_h
#define RHGenericDriver_h

#include <RadioHead.h>

// Defines bits of the FLAGS header reserved for use by the RadioHead library and 
// the flags available for use by applications
#define RH_FLAGS_RESERVED                 0xf0
#define RH_FLAGS_APPLICATION_SPECIFIC     0x0f
#define RH_FLAGS_NONE                     0

// Default timeout for waitCAD() in ms
#define RH_CAD_DEFAULT_TIMEOUT            10000

/////////////////////////////////////////////////////////////////////
/// \class RHGenericDriver RHGenericDriver.h <RHGenericDriver.h>
/// \brief Abstract base class for a RadioHead driver.
///
/// This class defines the functions that must be provided by any RadioHead driver.
/// Different types of driver will implement all the abstract functions, and will perhaps override 
/// other functions in this subclass, or perhaps add new functions specifically required by that driver.
/// Do not directly instantiate this class: it is only to be subclassed by driver classes.
///
/// Subclasses are expected to implement a half-duplex, unreliable, error checked, unaddressed packet transport.
/// They are expected to carry a message payload with an appropriate maximum length for the transport hardware
/// and to also carry unaltered 4 message headers: TO, FROM, ID, FLAGS
///
/// \par Headers
///
/// Each message sent and received by a RadioHead driver includes 4 headers:
/// -TO The node address that the message is being sent to (broadcast RH_BROADCAST_ADDRESS (255) is permitted)
/// -FROM The node address of the sending node
/// -ID A message ID, distinct (over short time scales) for each message sent by a particilar node
/// -FLAGS A bitmask of flags. The most significant 4 bits are reserved for use by RadioHead. The least
/// significant 4 bits are reserved for applications.
class RHGenericDriver
{
public:
    /// \brief Defines different operating modes for the transport hardware
    ///
    /// These are the different values that can be adopted by the _mode variable and 
    /// returned by the mode() member function,
    typedef enum
    {
	RHModeInitialising = 0, ///< Transport is initialising. Initial default value until init() is called..
	RHModeSleep,            ///< Transport hardware is in low power sleep mode (if supported)
	RHModeIdle,             ///< Transport is idle.
	RHModeTx,               ///< Transport is in the process of transmitting a message.
	RHModeRx,               ///< Transport is in the process of receiving a message.
	RHModeCad               ///< Transport is in the process of detecting channel activity (if supported)
    } RHMode;

    /// Constructor
    RHGenericDriver();

    /// Generic destructor to prevent warnings when objects are dynamically allocated
    virtual ~RHGenericDriver() {};

    /// Initialise the Driver transport hardware and software.
    /// Make sure the Driver is properly configured before calling init().
    /// \return true if initialisation succeeded.
    virtual bool init();

    /// Tests whether a new message is available
    /// from the Driver. 
    /// On most drivers, if there is an uncollected received message, and there is no message
    /// currently bing transmitted, this will also put the Driver into RHModeRx mode until
    /// a message is actually received by the transport, when it will be returned to RHModeIdle.
    /// This can be called multiple times in a timeout loop.
    /// \return true if a new, complete, error-free uncollected message is available to be retreived by recv().
    virtual bool available() = 0;

    /// Turns the receiver on if it not already on.
    /// If there is a valid message available, copy it to buf and return true
    /// else return false.
    /// If a message is copied, *len is set to the length (Caution, 0 length messages are permitted).
    /// You should be sure to call this function frequently enough to not miss any messages
    /// It is recommended that you call it in your main loop.
    /// \param[in] buf Location to copy the received message
    /// \param[in,out] len Pointer to available space in buf. Set to the actual number of octets copied.
    /// \return true if a valid message was copied to buf
    virtual bool recv(uint8_t* buf, uint8_t* len) = 0;

    /// Waits until any previous transmit packet is finished being transmitted with waitPacketSent().
    /// Then optionally waits for Channel Activity Detection (CAD) 
    /// to show the channnel is clear (if the radio supports CAD) by calling waitCAD().
    /// Then loads a message into the transmitter and starts the transmitter. Note that a message length
    /// of 0 is NOT permitted. If the message is too long for the underlying radio technology, send() will
    /// return false and will not send the message.
    /// \param[in] data Array of data to be sent
    /// \param[in] len Number of bytes of data to send (> 0)
    /// specify the maximum time in ms to wait. If 0 (the default) do not wait for CAD before transmitting.
    /// \return true if the message length was valid and it was correctly queued for transmit. Return false
    /// if CAD was requested and the CAD timeout timed out before clear channel was detected.
    virtual bool send(const uint8_t* data, uint8_t len) = 0;

    /// Returns the maximum message length 
    /// available in this Driver.
    /// \return The maximum legal message length
    virtual uint8_t maxMessageLength() = 0;

    /// Starts the receiver and blocks until a valid received 
    /// message is available.
    virtual void            waitAvailable();

    /// Blocks until the transmitter 
    /// is no longer transmitting.
    virtual bool            waitPacketSent();

    /// Blocks until the transmitter is no longer transmitting.
    /// or until the timeout occuers, whichever happens first
    /// \param[in] timeout Maximum time to wait in milliseconds.
    /// \return true if the radio completed transmission within the timeout period. False if it timed out.
    virtual bool            waitPacketSent(uint16_t timeout);

    /// Starts the receiver and blocks until a received message is available or a timeout
    /// \param[in] timeout Maximum time to wait in milliseconds.
    /// \return true if a message is available
    virtual bool            waitAvailableTimeout(uint16_t timeout);

    // Bent G Christensen (bentor@gmail.com), 08/15/2016
    /// Channel Activity Detection (CAD).
    /// Blocks until channel activity is finished or CAD timeout occurs.
    /// Uses the radio's CAD function (if supported) to detect channel activity.
    /// Implements random delays of 100 to 1000ms while activity is detected and until timeout.
    /// Caution: the random() function is not seeded. If you want non-deterministic behaviour, consider
    /// using something like randomSeed(analogRead(A0)); in your sketch.
    /// Permits the implementation of listen-before-talk mechanism (Collision Avoidance).
    /// Calls the isChannelActive() member function for the radio (if supported) 
    /// to determine if the channel is active. If the radio does not support isChannelActive(),
    /// always returns true immediately
    /// \return true if the radio-specific CAD (as returned by isChannelActive())
    /// shows the channel is clear within the timeout period (or the timeout period is 0), else returns false.
    virtual bool            waitCAD();

    /// Sets the Channel Activity Detection timeout in milliseconds to be used by waitCAD().
    /// The default is 0, which means do not wait for CAD detection.
    /// CAD detection depends on support for isChannelActive() by your particular radio.
    void setCADTimeout(unsigned long cad_timeout);

    /// Determine if the currently selected radio channel is active.
    /// This is expected to be subclassed by specific radios to implement their Channel Activity Detection
    /// if supported. If the radio does not support CAD, returns true immediately. If a RadioHead radio 
    /// supports isChannelActive() it will be documented in the radio specific documentation.
    /// This is called automatically by waitCAD().
    /// \return true if the radio-specific CAD (as returned by override of isChannelActive()) shows the
    /// current radio channel as active, else false. If there is no radio-specific CAD, returns false.
    virtual bool            isChannelActive();

    /// Sets the address of this node. Defaults to 0xFF. Subclasses or the user may want to change this.
    /// This will be used to test the adddress in incoming messages. In non-promiscuous mode,
    /// only messages with a TO header the same as thisAddress or the broadcast addess (0xFF) will be accepted.
    /// In promiscuous mode, all messages will be accepted regardless of the TO header.
    /// In a conventional multinode system, all nodes will have a unique address 
    /// (which you could store in EEPROM).
    /// You would normally set the header FROM address to be the same as thisAddress (though you dont have to, 
    /// allowing the possibilty of address spoofing).
    /// \param[in] thisAddress The address of this node.
    virtual void setThisAddress(uint8_t thisAddress);

    /// Sets the TO header to be sent in all subsequent messages
    /// \param[in] to The new TO header value
    virtual void           setHeaderTo(uint8_t to);

    /// Sets the FROM header to be sent in all subsequent messages
    /// \param[in] from The new FROM header value
    virtual void           setHeaderFrom(uint8_t from);

    /// Sets the ID header to be sent in all subsequent messages
    /// \param[in] id The new ID header value
    virtual void           setHeaderId(uint8_t id);

    /// Sets and clears bits in the FLAGS header to be sent in all subsequent messages
    /// First it clears he FLAGS according to the clear argument, then sets the flags according to the 
    /// set argument. The default for clear always clears the application specific flags.
    /// \param[in] set bitmask of bits to be set. Flags are cleared with the clear mask before being set.
    /// \param[in] clear bitmask of flags to clear. Defaults to RH_FLAGS_APPLICATION_SPECIFIC
    ///            which clears the application specific flags, resulting in new application specific flags
    ///            identical to the set.
    virtual void           setHeaderFlags(uint8_t set, uint8_t clear = RH_FLAGS_APPLICATION_SPECIFIC);

    /// Tells the receiver to accept messages with any TO address, not just messages
    /// addressed to thisAddress or the broadcast address
    /// \param[in] promiscuous true if you wish to receive messages with any TO address
    virtual void           setPromiscuous(bool promiscuous);

    /// Returns the TO header of the last received message
    /// \return The TO header
    virtual uint8_t        headerTo();

    /// Returns the FROM header of the last received message
    /// \return The FROM header
    virtual uint8_t        headerFrom();

    /// Returns the ID header of the last received message
    /// \return The ID header
    virtual uint8_t        headerId();

    /// Returns the FLAGS header of the last received message
    /// \return The FLAGS header
    virtual uint8_t        headerFlags();

    /// Returns the most recent RSSI (Receiver Signal Strength Indicator).
    /// Usually it is the RSSI of the last received message, which is measured when the preamble is received.
    /// If you called readRssi() more recently, it will return that more recent value.
    /// \return The most recent RSSI measurement in dBm.
    virtual int16_t        lastRssi();

    /// Returns the operating mode of the library.
    /// \return the current mode, one of RF69_MODE_*
    virtual RHMode          mode();

    /// Sets the operating mode of the transport.
    virtual void            setMode(RHMode mode);

    /// Sets the transport hardware into low-power sleep mode
    /// (if supported). May be overridden by specific drivers to initialte sleep mode.
    /// If successful, the transport will stay in sleep mode until woken by 
    /// changing mode it idle, transmit or receive (eg by calling send(), recv(), available() etc)
    /// \return true if sleep mode is supported by transport hardware and the RadioHead driver, and if sleep mode
    ///         was successfully entered. If sleep mode is not suported, return false.
    virtual bool    sleep();

    /// Prints a data buffer in HEX.
    /// For diagnostic use
    /// \param[in] prompt string to preface the print
    /// \param[in] buf Location of the buffer to print
    /// \param[in] len Length of the buffer in octets.
    static void    printBuffer(const char* prompt, const uint8_t* buf, uint8_t len);

    /// Returns the count of the number of bad received packets (ie packets with bad lengths, checksum etc)
    /// which were rejected and not delivered to the application.
    /// Caution: not all drivers can correctly report this count. Some underlying hardware only report
    /// good packets.
    /// \return The number of bad packets received.
    virtual uint16_t       rxBad();

    /// Returns the count of the number of 
    /// good received packets
    /// \return The number of good packets received.
    virtual uint16_t       rxGood();

    /// Returns the count of the number of 
    /// packets successfully transmitted (though not necessarily received by the destination)
    /// \return The number of packets successfully transmitted
    virtual uint16_t       txGood();

protected:

    /// The current transport operating mode
    volatile RHMode     _mode;

    /// This node id
    uint8_t             _thisAddress;
    
    /// Whether the transport is in promiscuous mode
    bool                _promiscuous;

    /// TO header in the last received mesasge
    volatile uint8_t    _rxHeaderTo;

    /// FROM header in the last received mesasge
    volatile uint8_t    _rxHeaderFrom;

    /// ID header in the last received mesasge
    volatile uint8_t    _rxHeaderId;

    /// FLAGS header in the last received mesasge
    volatile uint8_t    _rxHeaderFlags;

    /// TO header to send in all messages
    uint8_t             _txHeaderTo;

    /// FROM header to send in all messages
    uint8_t             _txHeaderFrom;

    /// ID header to send in all messages
    uint8_t             _txHeaderId;

    /// FLAGS header to send in all messages
    uint8_t             _txHeaderFlags;

    /// The value of the last received RSSI value, in some transport specific units
    volatile int16_t     _lastRssi;

    /// Count of the number of bad messages (eg bad checksum etc) received
    volatile uint16_t   _rxBad;

    /// Count of the number of successfully transmitted messaged
    volatile uint16_t   _rxGood;

    /// Count of the number of bad messages (correct checksum etc) received
    volatile uint16_t   _txGood;
    
    /// Channel activity detected
    volatile bool       _cad;

    /// Channel activity timeout in ms
    unsigned int        _cad_timeout;

private:

};

#endif