Example CAN imp

CAN.c

//CAN SAMPLE AT91SAM7X256 48MHz YAGARTO

//BRP = ((1 / (CAN_baudrate *16bit))* 48MHz) -1
//sample: 500kbaud @48MHz ((1/(500000*16))*48MHz)-1 =5  =>CAN_BR = 0x053255;
//sample: 100kbaud @48MHz ((1/(100000*16))*48MHz)-1 =29 =>CAN_BR = 0x1D3255;
#define CAN_BR_500K      0x00053255
#define CAN_BR_250K      0x000B3255
#define CAN_BR_200K      0x000E3255
#define CAN_BR_150K      0x00133255
#define CAN_BR_125K      0x00173255
#define CAN_BR_100K      0x001D3255
#define CAN_BR_83K       0x00233255
#define CAN_BR_75K       0x00273255
#define CAN_BR_50K       0x003B3255
#define CAN_BR_25K       0x00773255

//can message structure
typedef struct s_can_message        
{
    unsigned int    ID;      //ID
    unsigned char  DLC;   //data length
    unsigned int   ML,MH;   //l,h data
}can_message;

can_message rm[4];      //receive message
can_message tm[4];      //transmit message

unsigned int  status;   //status
unsigned char f_can0;   //flag can receive message
unsigned short FILTER1 = 0x05AA;//filter ID

//CAN interrupt
void CANIrqHandler (void)
{
    //reset interrupt
    status = AT91C_BASE_CAN->CAN_SR;
    //check for enabled interrupt
    status &= AT91C_BASE_CAN->CAN_IMR;
    //WAKEUP interrupt
    if(status & AT91C_CAN_WAKEUP)
    {
        AT91C_BASE_CAN->CAN_IDR = AT91C_CAN_WAKEUP;
    }
    //MB0 INT
    if(status &  AT91C_CAN_MB0)
    {
        //reset timer
        AT91C_BASE_CAN->CAN_TCR = AT91C_CAN_MB0;
        //get received ID
        rm[0].ID =(unsigned int)((AT91C_BASE_CAN->CAN_MB0.CAN_MB_MID >> 18))& 0x07FF;
        rm[0].DLC =(unsigned char)((AT91C_BASE_CAN->CAN_MB0.CAN_MB_MSR >>16) & 0x0F);
        rm[0].ML =AT91C_BASE_CAN->CAN_MB0.CAN_MB_MDL;
        rm[0].MH =AT91C_BASE_CAN->CAN_MB0.CAN_MB_MDH;
        //set flag
        f_can0 =1;
    }
}

//init CAN
void can_init(void)
{
    //enable Pins
    AT91C_BASE_PIOA->PIO_ASR = AT91C_PA19_CANRX|AT91C_PA20_CANTX;
    AT91C_BASE_PIOA->PIO_PDR = AT91C_PA19_CANRX|AT91C_PA20_CANTX;
    //enable Clock
    AT91C_BASE_PMC->PMC_PCER = 1 << AT91C_ID_CAN;
    //init AIC-CAN
    AT91C_BASE_AIC->AIC_IDCR = 1 << AT91C_ID_CAN;
    //disable Reception Mailbox 0 interrupt
    AT91C_BASE_CAN->CAN_IDR = AT91C_CAN_MB0 | AT91C_CAN_MB1;
    AT91C_BASE_AIC->AIC_SMR[AT91C_ID_CAN] = 0x7;      //set prior
    AT91C_BASE_AIC->AIC_SVR[AT91C_ID_CAN] = (unsigned int) CANIrqHandler;
    AT91C_BASE_AIC->AIC_IECR = 1 << AT91C_ID_CAN;      //disable
    AT91C_BASE_AIC->AIC_ICCR = 1 << AT91C_ID_CAN;     
    //set baudrate
    AT91C_BASE_CAN->CAN_BR = CAN_BR_100K;
    //enable WAKEUP Int
    AT91C_BASE_CAN->CAN_IER = AT91C_CAN_WAKEUP;
    //enable Error Ints
    AT91C_BASE_CAN->CAN_IER = AT91C_CAN_AERR | AT91C_CAN_CERR;// |AT91C_CAN_SERR;//| AT91C_CAN_BERR
    // Configure Mailbox 0, RX
    AT91C_BASE_CAN_MB0->CAN_MB_MMR    = AT91C_CAN_MOT_RXOVERWRITE;
    AT91C_BASE_CAN_MB0->CAN_MB_MAM    = 0x000 << 18;   //reset acceptance
    AT91C_BASE_CAN_MB0->CAN_MB_MID    = 0x000 << 18;   //reset filter

    //mailbox 1 transmission low byte first
    AT91C_BASE_CAN_MB1->CAN_MB_MAM=0x00000000;   //accept all  
    AT91C_BASE_CAN_MB1->CAN_MB_MMR=AT91C_CAN_MOT_TX;//enable TX and set MRDY

    // Enable Reception Mailbox 0 interrupt
    AT91C_BASE_CAN->CAN_IER = AT91C_CAN_MB0;// | AT91C_CAN_MB1;

    // Clear and trigger Transfer
    AT91C_BASE_CAN->CAN_TCR = AT91C_CAN_MB0;
    AT91C_BASE_CAN->CAN_MB0.CAN_MB_MCR = AT91C_CAN_MTCR;
    // Enable CAN
    AT91C_BASE_CAN->CAN_MR = AT91C_CAN_CANEN; //
    // Enable CAN in "Listen Only" mode
    //AT91C_BASE_CAN->CAN_MR = AT91C_CAN_ABM | AT91C_CAN_CANEN;
}

//CAN_TX transmit data via MB1
void can_tx(unsigned char tx_number)
{
    //set MB1
    AT91C_BASE_CAN_MB1->CAN_MB_MID=tm[tx_number].ID<<18;   //11 bit Part A ID
    AT91C_BASE_CAN_MB1->CAN_MB_MDH=tm[tx_number].MH;   //data high
    AT91C_BASE_CAN_MB1->CAN_MB_MDL=tm[tx_number].ML;   //data low
    if(AT91C_BASE_CAN->CAN_SR & AT91C_CAN_MB1)       //if mailbox ready
    {
        //send data  
        AT91C_BASE_CAN->CAN_MB1.CAN_MB_MCR =(tm[tx_number].DLC<<16)|AT91C_CAN_MTCR;
        //wait until transmission ready
        while(!(AT91C_BASE_CAN_MB1->CAN_MB_MSR & AT91C_CAN_MRDY)){}  
    }                     //end mailbox ready
}

...
//set and transmit data
tm[0].ID=0x55C<<18;   //11 bit Part A ID
tm[0].MH=0x00000000;   //data high
tm[0].ML=0x00000004;   //data low
tm[0].DLC =8;
can_tx(0);     
...

...
//set filter to read all
AT91C_BASE_AIC->AIC_IDCR = 1 << AT91C_ID_CAN;
// Configure Mailbox 0, RX
AT91C_BASE_CAN_MB0->CAN_MB_MID  = 0x000 << 18;
AT91C_BASE_AIC->AIC_IECR = 1 << AT91C_ID_CAN;   //enable
AT91C_BASE_AIC->AIC_ICCR = 1 << AT91C_ID_CAN;  
...

...
//set filter
AT91C_BASE_AIC->AIC_IDCR = 1 << AT91C_ID_CAN;
// Configure Mailbox 0, RX
AT91C_BASE_CAN->CAN_MB0.CAN_MB_MID=FILTER1<<18;   //11 bit Part A ID
AT91C_BASE_CAN_MB0->CAN_MB_MID  = 0x000 << 18;
AT91C_BASE_AIC->AIC_IECR = 1 << AT91C_ID_CAN;   //enable
AT91C_BASE_AIC->AIC_ICCR = 1 << AT91C_ID_CAN;