About MM9Z1_638 CAN interface

[ztzzzttt]

Hi, Bro

We use DEMO CODE:RD9Z1_638_12VLA_DEMO on MM9Z1638 Borad  to test msCAN  interface,and we don't placed a Oscillator,

so I modified two places:PICTURE 1

but I can't get correct rusult，500kbps，

actually get 833.3kbps  PICTURE2。

Is there some thing has to set，or make some mistakes。

                               THANKS FOR YOUR HELP

[Q_man]

Hi,

-what hardware do you use KIT9Z1J638EVM?

-CAN will require an external oscillator to achieve the required CAN clock accuracy

-the CAN bit timing (time quanta, etc.) is set in the msCANcfg.h file:

/******************************************************************************
* Define msCAN module clock source: BUSCLK or MCGERCLK
* Permitted values: BUSCLK:   Bus clock is used as clock source 
*                   MCGERCLK: Oscillator clock is used as clock source
******************************************************************************/
#define CLKSRC_CAN0 MCGERCLK
/******************************************************************************
* Define clock prescaler for msCAN module: permitted values 1 to 64
* msCAN module clock = CLKSRC_CAN / PRESCALER_CAN
* Set different Prescaler for all CAN Channels, in case the Oscillator Frequency is 8M
* Note: User can carefully change this part to get different bitrate
******************************************************************************/
//#define PRESCALER_CAN0          (1)       // 1000kbps, if CANBTR0 AND CANBTR1 IN the driver not changed
#define PRESCALER_CAN0          (2)       // 500kbps, if CANBTR0 AND CANBTR1 IN the driver not changed
/******************************************************************************
* Define msCAN module bit timing
*
* Permitted values:
*                   PHASE_SEG1_CAN: 1 to 16 time quanta
*                   PHASE_SEG2_CAN: 1 to 8 time quanta
* Bit time = (1 + TIME_SEG1_CAN + TIME_SEG2_CAN) * time quanta
* Note: User can carefully change this part to get different bitrate
******************************************************************************/
#define TIME_SEG1_CAN0          (7)
#define TIME_SEG2_CAN0          (8)
/******************************************************************************
* Define msCAN module re-synchronisation jump width
* Permitted values: 1 to smaller of 4 and PHASE_SEG1_CAN time quanta
******************************************************************************/
#define RJW_CAN0               (2)

[ztzzzttt]

Thanks for your helps.

      I adjusted the one paramete,

         CHANGED "REFDIV(16)"    TO  "REFDIV(8)"    

 and now  I can send data from the CAN bus, through CAN- Monitor connected PC, PC can get the correct data, however, PC sends data to the board, the board can't receive PC data ("SET FRAME ID： 0x10"),   can't get   "NEWDATA" ,

I use the oscilloscope to test the TX and RX pin on board, oddly, TX and RX when sending data have the same waveform.

I don't know where's wrong.    Can you give me some advice, or an example.

[Q_man · Accepted solution]

Can you please specify which hardware you use?

Your desired CAN speed is 500kBaud?

In principle you have to configure a mail box for a receiving message object:

Example:

- in the msCANID.h file configure a message object and the desired CAN ID:

      /* Message Object 2 */
      #define MO2_ID_TYPE_CAN0      CAN_STANDARD
      #define MO2_ID_CAN0           0x303

- initialze mail box for message object 2 (e.g. in main.c)

        Config_CAN_MB(CAN0, 2, RXDF, 2);  //configure mail box 2 for RXDF for message object 2

- check mail box 2 (e.g. in main.c)

        // read message object .....
        (void) Check_CAN_MB_Status(CAN0, 2, &mbStat);
        if((mbStat.Status == NEWDATA)||(mbStat.Status == OVERRUN)) {               // new data ?

Also check out the CAN driver Manual (in the Sources/drivers/msCANDriver/Manual/Manual.pdf file)

[ztzzzttt]

THANK YOU FOR YOUR HELP！ 

I have set 800k Baud and goten RX and TX correct data 。thankyou！