I'm trying CAN bus communication on s12g128.I tried http://cache.freescale.com/files/microcontrollers/doc/app_note/AN4455SW.zip CAN example but i didnt work.
/******************************************************************************
Function Name : main
Engineer : r28318
Date : 09/06/09
Parameters : NONE
Returns : NONE
Notes : main routine called by Startup.c.
******************************************************************************/
void main(void)
{
byte txbuffer;
ECLKCTL_NECLK = 0; /* Enable ECLK = Bus Clock */
/* initialise the system clock PEE - 64MHz VCO, 32MHz Bus CLK, from 8MHz Crystal */
CPMUSYNR = 0x47; /* SYNDIV = 7, VCO frequency 48 - 64 MHz */
CPMUREFDIV = 0x80; /* REFDIV = 0 REFCLK frequency 6 - 12 MHz */
CPMUPOSTDIV = 0x01; /* POSTDIV = 1 */
CPMUCLKS_PLLSEL = 1; /* PLLSEL = 1 */
while (!CPMUCLKS_PLLSEL); /* Verify CPMUCLKS configuration */
CPMUOSC_OSCE = 1; /* Enable Oscillator OSCE = 1 */
while(!CPMUFLG_UPOSC); /* wait for OSC to stabilise */
while(!CPMUFLG_LOCK); /* wait for PLL to lock */
/* LEDs */
PTT = 0xF0; /* Initialise PORT T all high; turn off LEDs */
DDRT = 0xF0; /* PORTT 7:4 as outputs */
/* Push Buttons */
PER1AD = 0xF0; /* Enable Port PAD Pulls */
PPS1AD = 0x00; /* Eanble as Pull-Ups */
ATDDIEN = 0x00F0; /* Enable PAD[7:4] as inputs */
/* Initialise the CAN */
CANCTL1_CANE = 1; /* enable CAN module */
CANCTL0 = 0x01; /* enter init mode */
while(!(CANCTL1_INITAK)); /* wait for init mode */
CANCTL1 = 0xA0; /* enable CAN module, Loopback Mode, Ext OSC */
CANBTR0 = 0xC3; /* sync jump - 4 Tq clocks, prescalar = 3 */
CANBTR1 = 0x3A; /* Tseg = 3, Tseg1 = 10, 1 sample per bit */
CANIDAC = 0x10; /* four 16-bit filters */
CANIDAR0 = 0x20; /* Filter 0, ID=0x100 Standard Identifier */
CANIDMR0 = 0x00;
CANIDAR1 = 0x00;
CANIDMR1 = 0x07; /* AM[2:0] = 7 to receive standard identifiers */
CANIDAR2 = 0x00; /* Filter 1, ID=0x0000 */
CANIDMR2 = 0x00;
CANIDAR3 = 0x00;
CANIDMR3 = 0x07; /* AM[2:0] = 7 to receive standard identifiers */
CANIDAR4 = 0x00; /* Filter 2, ID=0x0000 */
CANIDMR4 = 0x00;
CANIDAR5 = 0x00;
CANIDMR5 = 0x07; /* AM[2:0] = 7 to receive standard identifiers */
CANIDAR6 = 0x00; /* Filter 3, ID=0x0000 */
CANIDMR6 = 0x00;
CANIDAR7 = 0x00;
CANIDMR7 = 0x07; /* AM[2:0] = 7 to receive standard identifiers */
CANCTL0 = 0x00; /* exit init mode */
while(CANCTL1_INITAK); /* wait until module exits init mode */
while(!(CANCTL0_SYNCH)); /* wait for CAN module to synch */
CANRFLG = 0xC3; /* reset Rx flags */
for(;;)
{
while (!CANTFLG); /* Wait for empty Tx Buffer */
CANTBSEL = CANTFLG; /* Select the empty Tx Buffer */
txbuffer = CANTBSEL; /* Save the empty buffer */
CANTXIDR0 = 0x20; /* load message id value to ID regs */
CANTXIDR1 = 0x00;
CANTXIDR2 = 0x00;
CANTXIDR3 = 0x00;
// while(PT1AD == 0xFF);
CANTXDSR0 = 0x55; /* load data to send */
CANTXDLR = 0xFF; /* set data length */
CANTXTBPR = 0x80; /* set data buffer priority */
CANTFLG = txbuffer; /* start transmission */
while(!(CANTFLG & txbuffer)); /* wait for Tx to complete */
if(CANRFLG_RXF) /* has a message been received ? */
{
PTT = CANRXDSR0; /* Display transmitted PORTB on LEDs */
CANRFLG_RXF = 1; /* Clear RXF */
}
}
}
#pragma CODE_SEG DEFAULT
