FlexCAN.h

// -------------------------------------------------------------
// a simple Arduino Teensy 3.1/3.2/3.6 CAN driver
// by teachop
// dual CAN support for MK66FX1M0 by Pawelsky
//
#ifndef __FLEXCAN_H__
#define __FLEXCAN_H__

#include <Arduino.h>

#define FlexCAN_MAILBOX_TX_BUFFER_SUPPORT  // helper definition for handling different FlexCAN revisions
#define FlexCAN_DYNAMIC_BUFFER_SUPPORT  // helper definition for handling different FlexCAN revisions

#if !defined(SIZE_RX_BUFFER)
#define SIZE_RX_BUFFER  32 // receive incoming ring buffer size
#endif

#if !defined(SIZE_TX_BUFFER)
#define SIZE_TX_BUFFER  16 // transmit ring buffer size
#endif

#define SIZE_LISTENERS  4  // number of classes that can register as listeners on each CAN bus
#define NUM_MAILBOXES   16 // architecture specific but all Teensy 3.x boards have 16 mailboxes
#define IRQ_PRIORITY    64 // 0 = highest, 255 = lowest

#define COLLECT_CAN_STATS

typedef struct CAN_message_t {
    uint32_t id;          // can identifier
    uint16_t timestamp;   // FlexCAN time when message arrived
    struct {
        uint8_t extended:1; // identifier is extended (29-bit)
        uint8_t remote:1;   // remote transmission request packet type
        uint8_t overrun:1;  // message overrun
        uint8_t reserved:5;
    } flags;
    uint8_t len;          // length of data
    uint8_t buf[8];
} CAN_message_t;

typedef struct CAN_filter_t {
    uint32_t id;
    struct {
        uint8_t extended:1;  // identifier is extended (29-bit)
        uint8_t remote:1;    // remote transmission request packet type
        uint8_t reserved:6;
    } flags;
} CAN_filter_t;

// statistics about the CAN interface

typedef struct CAN_stats_t {
    bool     enabled;           // enable collecting statistics
    uint32_t ringRxMax;         // number of entries in the ring buffer
    uint32_t ringRxHighWater;   // maximum entries used in the ring buffer
    uint32_t ringRxFramesLost;  // total number of frames lost
    uint32_t ringTxMax;         // number of entries in the ring buffer
    uint32_t ringTxHighWater;   // maximum entries used in the ring buffer
    struct {
        uint32_t refCount;        // mailbox reference (use) count
        uint32_t overrunCount;    // mailbox message overrun count
    } mb[NUM_MAILBOXES];
} CAN_stats_t;

// ring buffer data structure

typedef struct ringbuffer_t {
    volatile uint16_t head;
    volatile uint16_t tail;
    uint16_t size;
    volatile CAN_message_t *buffer;
} ringbuffer_t;

// for backwards compatibility with previous structure members

#define	ext flags.extended
#define	rtr flags.remote

class CANListener
{
public:
    CANListener ();

    virtual bool frameHandler (CAN_message_t &frame, int mailbox, uint8_t controller);
    virtual void txHandler (int mailbox, uint8_t controller);

    void attachMBHandler (uint8_t mailBox);
    void detachMBHandler (uint8_t mailBox);
    void attachGeneralHandler (void);
    void detachGeneralHandler (void);

private:
    uint32_t callbacksActive; // bitfield indicating which callbacks are installed (for object oriented callbacks only)

    friend class FlexCAN;     // class has to have access to the the guts of this one
};

// -------------------------------------------------------------

class FlexCAN
{
private:
    uint32_t flexcanBase;
    struct CAN_filter_t MBFilters[NUM_MAILBOXES];
    static struct CAN_filter_t defaultMask;
    void mailbox_int_handler (uint8_t mb, uint32_t ul_status);
    CANListener *listener[SIZE_LISTENERS];

    ringbuffer_t txRing;
    volatile CAN_message_t *tx_buffer;
    ringbuffer_t rxRing;
    volatile CAN_message_t *rx_buffer;
    ringbuffer_t * txRings[NUM_MAILBOXES];
    
    bool IrqEnabled;
    uint32_t IrqMessage;

    void writeTxRegisters (const CAN_message_t &msg, uint8_t buffer);
    void readRxRegisters (CAN_message_t &msg, uint8_t buffer);

    void initRingBuffer (ringbuffer_t &ring, volatile CAN_message_t *buffer, uint32_t size);
    bool addToRingBuffer (ringbuffer_t &ring, const CAN_message_t &msg);
    bool removeFromRingBuffer (ringbuffer_t &ring, CAN_message_t &msg);
    bool isRingBufferEmpty (ringbuffer_t &ring);
    uint32_t ringBufferCount (ringbuffer_t &ring);

    void irqLock() { IrqEnabled=NVIC_IS_ENABLED(IrqMessage); NVIC_DISABLE_IRQ(IrqMessage); }
    void irqRelease() { if (IrqEnabled) NVIC_ENABLE_IRQ(IrqMessage); }
    
    void initializeBuffers();
    bool isInitialized() { return tx_buffer!=0; }
    void setPins(uint8_t txAlt, uint8_t rxAlt);
    void setBaudRate(uint32_t baud);
    void softReset();
    void halt();
    void exitHalt();
    void freeze();
    void waitFrozen();
    void waitNotFrozen();
    void waitReady();
    bool isFrozen();
    
    bool usesGlobalTxRing(uint8_t mbox) { return (mbox<getNumMailBoxes()?txRings[mbox]==0:true); }
    bool isTxBox(uint8_t mbox) { return (mbox>=getFirstTxBox() && mbox<getNumMailBoxes() ); }
    
#ifdef COLLECT_CAN_STATS
    CAN_stats_t stats;
#endif

protected:
    uint8_t numTxMailboxes;
    uint16_t sizeRxBuffer;
    uint16_t sizeTxBuffer;

public:
    FlexCAN (uint8_t id = 0);
    
    // Before begin, you can define rx buffer size. Default is SIZE_RX_BUFFER. This does not have effect after begin.
    void setRxBufferSize(uint16_t size) { if (!isInitialized() ) sizeRxBuffer=size; }
    
    // Before begin, you can define global tx buffer size. Default is SIZE_TX_BUFFER. This does not have effect after begin.
    void setTxBufferSize(uint16_t size) { if (!isInitialized() ) sizeTxBuffer=size; }
    
    // You can define mailbox specific tx buffer size. This can be defined only once per mailbox.
    // As default prioritized messages will not be buffered. If you define buffer size for mail box, the messages will be
    // buffered to own buffer, if necessary.
    void setMailBoxTxBufferSize(uint8_t mbox, uint16_t size);

    inline uint8_t getFirstTxBox() { return getNumMailBoxes()-numTxMailboxes; }
    inline uint8_t getLastTxBox() { return getNumMailBoxes()-1; }
    inline uint8_t getNumMailBoxes() { return NUM_MAILBOXES; }
    inline uint8_t getNumRxBoxes() { return getNumMailBoxes()-numTxMailboxes; }
    
    void begin (uint32_t baud = 250000, const CAN_filter_t &mask = defaultMask, uint8_t txAlt = 0, uint8_t rxAlt = 0);

    void setFilter (const CAN_filter_t &filter, uint8_t n);
    bool getFilter (CAN_filter_t &filter, uint8_t n);
    void setMask (uint32_t mask, uint8_t n);
    void end (void);
    uint32_t available (void);
    int write (const CAN_message_t &msg);
    int write (const CAN_message_t &msg, uint8_t n);
    int read (CAN_message_t &msg);
    uint32_t rxBufferOverruns (void)
    {
        return stats.ringRxFramesLost;
    };

#ifdef COLLECT_CAN_STATS
    void startStats (void)
    {
        stats.enabled = true;
    };
    void stopStats (void)
    {
        stats.enabled = false;
    };
    void clearStats (void);
    CAN_stats_t getStats (void)
    {
        return stats;
    };
#endif

    //new functionality added to header but not yet implemented. Fix me
    void setListenOnly (bool mode); //pass true to go into listen only mode, false to be in normal mode

    bool attachObj (CANListener *listener);
    bool detachObj (CANListener *listener);

    //int watchFor(); //allow anything through
    //int watchFor(uint32_t id); //allow just this ID through (automatic determination of extended status)
    //int watchFor(uint32_t id, uint32_t mask); //allow a range of ids through
    //int watchForRange(uint32_t id1, uint32_t id2); //try to allow the range from id1 to id2 - automatically determine base ID and mask

    uint8_t setNumTxBoxes (uint8_t txboxes);
    // Obsolete, for compatibility with version provided with Teensyduino
    uint8_t setNumTXBoxes (uint8_t txboxes) { return setNumTxBoxes(txboxes); }

    void message_isr (void);
    void bus_off_isr (void);
    void error_isr (void);
    void tx_warn_isr (void);
    void rx_warn_isr (void);
    void wakeup_isr (void);
};

extern FlexCAN Can0;
#ifdef __MK66FX1M0__
extern FlexCAN Can1;
#endif

#endif // __FLEXCAN_H__