mscan.c

CAN Example(MC9S12XDP512)

//////////////////////////////////////////////////////////////////////////////
//
// Sample for SofTec Microsystems SK-S12XDP512-A Starter Kit
// (Freescale code: EVB9S12XDP512)
//
// ---------------------------------------------------------------------------
//
// Copyright (c) 2005 SofTec Microsystems
// http://www.softecmicro.com/
//
//////////////////////////////////////////////////////////////////////////////

//////////////////////////////////////////////////////////////////////////////
//
// NOTES:
//
// - The following parameters are calculated according to application note
//   AN1798.
// - Only standard identifiers are used.
//
//////////////////////////////////////////////////////////////////////////////
//
// fNBT = 125000 bit/s
// CANCLK = 4000000 Hz
// tBUS = 25 ns (0.5 m * 5*10^-9 sm^-1)
// tTx = 500 ns
// tRx = 500 ns
//
// NBT = 10
// Tq = 0.75ns
// P = 3
// SYNC_SEG = 1Tq
// PROP_SEG = 3Tq
// PHASE_SEG1 = 3Tq
// PHASE_SEG2 = 3Tq
// RJW = 3
// OscToll = 1.181102%
//
//////////////////////////////////////////////////////////////////////////////

#include "mc9s12xdp512.h"
#include "mscan.h"

//////////////////////////////////////////////////////////////////////////////
// Variables
//////////////////////////////////////////////////////////////////////////////

unsigned char *can_periph[5] = {
    &CAN0CTL0,
    &CAN1CTL0,
    &CAN2CTL0,
    &CAN3CTL0,
    &CAN4CTL0
};

//////////////////////////////////////////////////////////////////////////////
// MSCAN Peripheral Initialization
//////////////////////////////////////////////////////////////////////////////

void MSCANInit(unsigned char can_num)
{
    unsigned char *can_pt;

    can_pt = can_periph[can_num];
    
    // If MSCAN peripheral is not in Initialization Mode, enables the Inizialization Mode Request
    if(!(can_pt[CANCTL1]&CANCTL1_INITAK_MASK))
        {
        can_pt[CANCTL0] = CANCTL0_INITRQ_MASK;
        while(!(can_pt[CANCTL1]&CANCTL1_INITAK_MASK))
            ;
        }

    // Enables MSCAN peripheral and chooses Oscillator Clock, Loop Disabled and Normal Operation
    can_pt[CANCTL1] = 0x80;

    // Configures SJW = 3Tq and Prescaler = 3
    can_pt[CANBTR0] = 0x82;

    // Configures One Sample, Time Segment 1 = 6Tq and Time Segment 2 = 3Tq
    can_pt[CANBTR1] = 0x25;

    // Disables all the Filters
    can_pt[CANIDMR_1B+0] = 0xFF;
    can_pt[CANIDMR_1B+1] = 0xFF;
    can_pt[CANIDMR_1B+2] = 0xFF;
    can_pt[CANIDMR_1B+3] = 0xFF;
    can_pt[CANIDMR_2B+0] = 0xFF;
    can_pt[CANIDMR_2B+1] = 0xFF;
    can_pt[CANIDMR_2B+2] = 0xFF;
    can_pt[CANIDMR_2B+3] = 0xFF;

    // Restarts MSCAN peripheral and waits for Initialization Mode exit
    can_pt[CANCTL0] = 0x00;
    while(can_pt[CANCTL1]&CANCTL1_INITAK_MASK)
        ;

    // Waits for MSCAN synchronization with the CAN bus
    while(!(can_pt[CANCTL0]&CANCTL0_SYNCH_MASK))
        ;
}

//////////////////////////////////////////////////////////////////////////////
// MSCAN Send Message Routine
//////////////////////////////////////////////////////////////////////////////

Bool MSCANSendMsg(unsigned char can_num, struct can_msg msg)
{
    unsigned char n_tx_buf = 0, i;
    unsigned char *can_pt;

    can_pt = can_periph[can_num];
    if(msg.len > 8)
        return(FALSE);
    if(!(can_pt[CANCTL0]&CANCTL0_SYNCH_MASK))
        return(FALSE);
    while(!(can_pt[CANTFLG]&MaskOR(n_tx_buf)))
        n_tx_buf = (n_tx_buf == MAX_TX_BUFFERS)? 0: (unsigned char)(n_tx_buf + 1);
    can_pt[CANTBSEL] = MaskOR(n_tx_buf);
    can_pt[CANTXIDR+0] = (unsigned char)(msg.id>>3);
    can_pt[CANTXIDR+1] = (unsigned char)(msg.id<<5);
    if(msg.RTR)
        can_pt[CANTXIDR+1] |= 0x10;
    for(i = 0; i < msg.len; i++)
        can_pt[CANTXDSR+i] = msg.data[i];
    can_pt[CANTXDLR] = msg.len;
    can_pt[CANTXTBPR] = msg.prty;
    can_pt[CANTFLG] = MaskOR(n_tx_buf);
    return(TRUE);
}

//////////////////////////////////////////////////////////////////////////////
// MSCAN Get Message Routine
//////////////////////////////////////////////////////////////////////////////

Bool MSCANGetMsg(unsigned char can_num, struct can_msg *msg)
{
    unsigned char i;
    unsigned char *can_pt;

    can_pt = can_periph[can_num];
    if(!(can_pt[CANRFLG]&CANRFLG_RXF_MASK))
        return(FALSE);
    if(can_pt[CANRXIDR+1]&0x08)
        return(FALSE);
    msg->id = ((can_pt[CANRXIDR+0]<<3)&0x0700) | (unsigned char)(can_pt[CANRXIDR+0]<<3) | (unsigned char)(can_pt[CANRXIDR+1]>>5);
    if(can_pt[CANRXIDR+1]&0x10)
        msg->RTR = TRUE;
    else
        msg->RTR = FALSE;
    msg->len = can_pt[CANRXDLR];
    for(i = 0; i < msg->len; i++)
        msg->data[i] = can_pt[CANRXDSR+i];
    can_pt[CANRFLG] = CANRFLG_RXF_MASK;
    return(TRUE);
}

//////////////////////////////////////////////////////////////////////////////
// MSCAN Check for Received Message Routine
//////////////////////////////////////////////////////////////////////////////

Bool MSCANCheckRcvdMsg(unsigned char can_num)
{
    unsigned char *can_pt;

    can_pt = can_periph[can_num];
    if(can_pt[CANRFLG]&CANRFLG_RXF_MASK)
        return(TRUE);
    return(FALSE);
}