Controller Area Network library for NUCLEO boards equipped with CAN peripheral.

Dependents:   Nucleo-Courtois CANBLE CANnucleo_Hello3 Nucleo_Serialprintf ... more

Controller Area Network library for the NUCLEO and DISCOVERY boards equipped with CAN peripheral


Information

Because CAN support has been finally implemented into the mbed library also for the ST boards there is no need to use the CANnucleo library anymore (however you may if you want). The CAN_Hello example is trying to demonstrate the mbed built-in CAN API with NUCLEO boards.


Provides CAN support for the following boards:

with the following features:

  • Easy to use. Delete the mbed library from your project and import the latest mbed-dev and CANnucleo libraries. In the mbed-dev library open the device.h file associated with the selected target board and add #undef DEVICE_CAN as follows:

device.h

#ifndef MBED_DEVICE_H
#define MBED_DEVICE_H

//=======================================
#define DEVICE_ID_LENGTH       24

#undef DEVICE_CAN

#include "objects.h"

#endif

See the CANnucleo_Hello demo for more details.

  • Automatic recovery from bus-off state can be enabled/disabled in the constructor (defaults to ENABLE).
  • Up to 14 filters (0 - 13) are available for the application to set up for message filtering performed by hardware.
    For more details see below or have a look at the comments in CANnucleo.cpp.
  • One CAN channel per NUCLEO board is supported. The CAN peripheral can be connected either to pins PA_11, PA_12 (Receiver, Transmitter) or to pins PB_8, PB_9 (Receiver, Transmitter). This is configured when creating a CAN instance.
  • Simplifies adding/getting data to/from a CAN message by using the << (append) and the >> (extract) operators.

Import programCANnucleo_Hello

Using CAN bus with NUCLEO boards (Demo for the CANnucleo library).



Filtering performed by the built-in CAN controller without disturbing the CPU

CANnucleo supports only mask mode and 32-bit filter scale. Identifier list mode filtering and 16-bit filter scale are not supported. There are 14 filters available (0 - 13) for the application to set up. Each filter is a 32-bit filter defined by a filter ID and a filter mask. If no filter is set up then no CAN message is accepted! That's why filter #0 is set up in the constructor to accept all CAN messages by default. On reception of a message it is compared with filter #0. If there is a match, the message is accepted and stored. If there is no match, the incoming identifier is then compared with the next filter. If the received identifier does not match any of the identifiers configured in the filters, the message is discarded by hardware without disturbing the software.

CAN filter function - designed to setup a CAN filter

int CAN::filter(unsigned int id, unsigned int mask, CANFormat format, int handle)

Parameters

id - 'Filter ID' defines the bit values to be compared with the corresponding received bits.

Mapping of 32-bits (4-bytes) :

STID[10:3]STID[2:0] EXID[17:13]EXID[12:5]EXID[4:0] IDE RTR 0
  • STID - Stardard Identifier bits
  • EXID - Extended Identifier bits
  • [x:y]- bit range
  • IDE - Identifier Extension bit (0 -> Standard Identifier, 1 -> Extended Identifier)
  • RTR - Remote Transmission Request bit (0 -> Remote Transmission Request, 1 -> Standard message)

mask - 'Filter mask' defines which bits of the 'Filter ID' are compared with the received bits and which are disregarded.
Mapping of 32-bits (4-bytes) :

STID[10:3]STID[2:0] EXID[17:13]EXID[12:5]EXID[4:0] IDE RTR 0
  • STID - Stardard Identifier bits
  • EXID - Extended Identifier bits
  • [x:y]- bit range
  • IDE - Identifier Extension bit
  • RTR - Remote Transmission Request bit
  • 1 -> bit is considered
  • 0 -> bit is disregarded

format - This parameter must be CANAny
handle - Selects the filter. This parameter must be a number between 0 and 13.
retval - 0 - successful, 1 - error, 2 - busy, 3 - time out

Example of filter set up and filtering

Let's assume we would like to accept only messages with standard identifier 0x207:

STID[15:0] = 0x207 = 00000010 00000111


We map the STID to filter ID by shifting the bits adequately:

Filter ID = STID << (16 + (15 - 10)) = STID << 21 = 01000000 11100000 00000000 00000000


To compare only the bits representing STID we set the filter mask appropriately:

Filter mask = 11111111 11100000 00000000 00000100 = 0xFFE00004
              |||||||| |||                    |
              -------- ---                    |
                  |     |                     |
           STID[10:3]  STID[2:0]             IDE


Recall that filter #0 has been set up in the constructor to accept all CAN messages by default. So we have to reconfigure it. If we were set up filter #1 here then filter #0 would accept all the messages and no message would reach filter #1!
To reconfigure (set up) filter #0 we call:

can.filter(0x207 << 21, 0xFFE00004, CANAny, 0);


            Only these bits of 'Filter id' (set to 1 here in 'Filter mask') are compared 
            with the corresponding bits of received message (the others are disregarded)
                                |
                 ---------------------------------
                 |||||||| |||                    |
   Filter mask = 11111111 11100000 00000000 00000100 (= 0xFFE00004)
   Filter id   = 01000000 11100000 00000000 00000000 (= 0x40E00000)
                 |||||||| |||                    |
                 ---------------------------------
                                |
            To accept the message the values of these bits must match.
            Otherwise the message is passed to the next filter or
            discarded if this was the last active filter.
                                |
                 ---------------------------------
                 |||||||| |||                    |
   Received id = 01000000 11100000 00000000 00000010 (= 0x40E00002)
                             ||||| |||||||| ||||| ||
                             -----------------------
                                         |
                          These bits (set to 0 in 'Filter mask') are disregarded (masked).
                          They can have arbitrary values.


NOTE: For the meaning of individual bits see the mapping of 32-bits explained above.

We can use the filter function to setup more (up to 14) CAN filters for example as follows:

can.filter(0x207 << 21, 0xFFE00004, CANAny, 0);    // filter #0
can.filter(0x251 << 21, 0xFFE00004, CANAny, 1);    // filter #1
can.filter(0x304 << 21, 0xFFE00004, CANAny, 2);    // filter #2
...

CANnucleo.h

Committer:
hudakz
Date:
2016-08-10
Revision:
22:ea766d08c9db
Parent:
21:d51e1617975f
Child:
23:c5d348e65e24

File content as of revision 22:ea766d08c9db:

/* mbed Microcontroller Library
 * Copyright (c) 2006-2013 ARM Limited
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 * Modified by Zoltan Hudak    <hudakz@inbox.com>
 *
 */
#ifndef CAN_NUCLEO_H
#define CAN_NUCLEO_H

#include "platform.h"
#include "can_api.h"
#include "can_helper.h"
#include "FunctionPointer.h"
    
namespace CANnucleo
{
    
/** CANMessage class
 */
class CANMessage : public CAN_Message
{

public:
    /** Creates empty CAN message.
     */
    CANMessage() : CAN_Message() {
        len    = 8;
        type   = CANData;
        format = CANStandard;
        id     = 0;
        memset(data, 0, 8);
    }

    /** Creates CAN message with specific content.
     */
    CANMessage(int _id, const char *_data, char _len = 8, CANType _type = CANData, CANFormat _format = CANStandard) {
        len    = _len & 0xF;
        type   = _type;
        format = _format;
        id     = _id;
        memcpy(data, _data, _len);
    }

    /** Creates CAN remote message.
     */
    CANMessage(int _id, CANFormat _format = CANStandard) {
        len    = 0;
        type   = CANRemote;
        format = _format;
        id     = _id;
        memset(data, 0, 8);
    }

    /*********************************************************************/
    /*********************************************************************/
    /*********************************************************************/
    /** Copy constructor.
     */
    CANMessage(const CANMessage& canMessage) {
        len     = canMessage.len;
        type    = canMessage.type;
        format  = canMessage.format;
        id      = canMessage.id;
        memcpy(data, canMessage.data, canMessage.len);
    }

    /** Clears CAN message content
     */
    void clear(void) {
        len    = 0;
        type   = CANData;
        format = CANStandard;
        id     = 0;
        memset(data, 0, 8);
    };

    /** Inserter operator: Appends data (value) to CAN message
     */
    template<class T>
    CANMessage &operator<<(const T val) {
        if(len + sizeof(T) <= 8) {
            *reinterpret_cast < T * > (&data[len]) = val;
            len += sizeof(T);
        } 
#if DEBUG
        else {
            printf("Error: Cannot append data because it exceeds CAN data length!\r\n");
        }
#endif
       return *this;
    }

    /** Extractor operator: Extracts data (value) from CAN message
     */
    template<class T>
    CANMessage &operator>>(T& val) {
        if(sizeof(T) <= len) {
            val = *reinterpret_cast < T * > (&data[0]);
            len -= sizeof(T);
            memcpy(data, data + sizeof(T), len);
        } 
#if DEBUG
        else {
            printf("Error: Cannot extract data because it exceeds CAN data length!\r\n");
        }
#endif
        return *this;
    }

};

/** A can bus client, used for communicating with can devices
 */
class CAN
{

public:
    /** Creates an CAN interface connected to specific pins.
     *
     *  @param rd read from transmitter
     *  @param td transmit to transmitter
     *
     * Example:
     * @code
     * #include "mbed.h"
     * #include "CAN.h"
     *
     * Ticker ticker;
     * DigitalOut led1(LED1);
     * CAN can(PA_11, PA_12);
     *
     * char counter = 0;
     *
     * void send() {
     *     if(can.write(CANMessage(1337, &counter, 1))) {
     *         printf("Message sent: %d\n", counter);
     *         counter++;
     *     }
     *     led1 = !led1;
     * }
     *
     * int main() {
     *     ticker.attach(&send, 1);
     *     CANMessage msg;
     *     while(1) {
     *         if(can.read(msg)) {
     *             printf("Message received: %d\n\n", msg.data[0]);
     *             led1 = !led1;
     *         }
     *         wait(0.2);
     *     }
     * }
     * @endcode
     */
     
    /** Constructor
     *
     * @param rd CAN receiver pin name
     * @param td CAN transmitter pin name
     * @param abom Automatic recovery from bus-off state (default value set to enabled)
     *
     */
    CAN(PinName rd, PinName td, FunctionalState abom = ENABLE);

    virtual ~CAN();

    /** Set the frequency of the CAN interface
     *
     *  @param hz The bus frequency in hertz
     *
     *  @returns
     *    1 if successful,
     *    0 otherwise
     */
    int frequency(int hz);

    /** Write a CANMessage to the bus.
     *
     *  @param msg The CANMessage to write.
     *
     *  @returns
     *    0 if write failed,
     *    1 if write was successful
     */
    int write(CANMessage msg);

    /** Read a CANMessage from the bus.
     *
     *  @param msg A CANMessage to read to.
     *  @param handle message filter handle (0 for any message)
     *
     *  @returns
     *    0 if no message arrived,
     *    1 if message arrived
     */
    int read(CANMessage &msg, int handle = 0);

    /** Reset CAN interface.
     *
     * To use after error overflow.
     */
    void reset();

    /** Puts or removes the CAN interface into silent monitoring mode
     *
     *  @param silent boolean indicating whether to go into silent mode or not
     */
    void monitor(bool silent);

    enum Mode {
        Reset = 0,
        Normal,
        Silent,
        LocalTest,
        GlobalTest,
        SilentTest
    };

    /** Change CAN operation to the specified mode
     *
     *  @param mode The new operation mode (CAN::Normal, CAN::Silent, CAN::LocalTest, CAN::GlobalTest, CAN::SilentTest)
     *
     *  @returns
     *    0 if mode change failed or unsupported,
     *    1 if mode change was successful
     */
    int mode(Mode mode);

    /** Filter out incomming messages
     *
     *  @param id the id to filter on
     *  @param mask the mask applied to the id
     *  @param format format to filter on (Default CANAny)
     *  @param handle message filter handle (Optional)
     *
     *  @retval  0 - successful
     *           1 - error
     *           2 - busy
     *           3 - time out 
     */
    int filter(unsigned int id, unsigned int mask, CANFormat format = CANAny, int handle = 0);

    /** Returns number of read errors to detect read overflow errors.
     */
    unsigned char rderror();

    /** Returns number of write errors to detect write overflow errors.
     */
    unsigned char tderror();

    enum IrqType {
        RxIrq = 0,
        TxIrq,
        EwIrq,
        DoIrq,
        WuIrq,
        EpIrq,
        AlIrq,
        BeIrq,
        IdIrq
    };

    /** Attach a function to call whenever a CAN frame received interrupt is
     *  generated.
     *
     *  @param fptr A pointer to a void function, or 0 to set as none
     *  @param event Which CAN interrupt to attach the member function to (CAN::RxIrq for message received, CAN::TxIrq for transmitted or aborted, CAN::EwIrq for error warning, CAN::DoIrq for data overrun, CAN::WuIrq for wake-up, CAN::EpIrq for error passive, CAN::AlIrq for arbitration lost, CAN::BeIrq for bus error)
     */
    void attach(void (*fptr)(void), IrqType type=RxIrq);

    /** Attach a member function to call whenever a CAN frame received interrupt
     *  is generated.
     *
     *  @param tptr pointer to the object to call the member function on
     *  @param mptr pointer to the member function to be called
     *  @param event Which CAN interrupt to attach the member function to (CAN::RxIrq for message received, TxIrq for transmitted or aborted, EwIrq for error warning, DoIrq for data overrun, WuIrq for wake-up, EpIrq for error passive, AlIrq for arbitration lost, BeIrq for bus error)
     */
    template<typename T>
    void attach(T* tptr, void (T::*mptr)(void), IrqType type=RxIrq) {
        HAL_NVIC_DisableIRQ(CAN_IRQ);
        if((tptr != NULL) && (mptr != NULL))
            _irq[type].attach(tptr, mptr);
        HAL_NVIC_EnableIRQ(CAN_IRQ);
    }

    static void _irq_handler(uint32_t id, CanIrqType type);

protected:
    mbed::FunctionPointer _irq[9];
};

} // namespace CANnucleo

#endif    // CAN_NUCLEO_H