Controller Area Network (CAN) - The HCS12/9S12: An Introduction to Software and Hardware Interfacing - page 682

hit1 ldab CAN1RDLR ; get the byte count of incoming data

beq rxfDone ; byte count 0, return

ldx #v1_line1 ; output “Voltage is”

jsr puts2lcd ; “

ldaa #$C4 ; set cursor to row 2 column 4

jsr cmd2LCD ; “

ldx #CAN1RDSR0 ; x points to data segment register 0

outLoop2 ldaa 1,x 1

jsr putc2lcd

dbne b,outLoop2

rxfDone rti

t1_line1 fcc “Temperature is”

dc.b 0

v1_line1 fcc “Voltage is”

dc.b 0

The C language version (compiled by ICC12 compiler) of the service routine is as follows:
#include “c:\iccv712\include\hcs12.h”

#include “c:\iccv712\include\delay.h”

#include “c:\iccv712\include\lcd_util.h”

void RxISR(void);

void open_can1(void);

char *t1Msg 5 “Temperature is”;

char *v1Msg 5 “Voltage is”;

int main (void)
{

asm( “ldd #_RxISR” ); //pass the interrupt vector of CAN1Rx interrupt

asm( “pshd” ); // “

asm( “ldd #21” ); //place the vector number of CAN1Rx in D

asm( “ldx $EEA4” );

asm( “jsr 0,X” );

open_can1();

openLCD();

CAN1RIER 5 0x01; /* enable CAN1 RXF interrupt only */

asm(“cli”);

while(1); /* wait for RXF interrupt */

return 0;

}
; *********************************************************************
// The following function handles the RXF interrupt. It checks if the RXF flag
// is set. If not, return. It also ignores the RTR request.
; *********************************************************************
#pragma interrupt_handler RxISR
void RxISR (void)
{

char tmp,i,*ptr;

if (!(CAN1RFLG & RXF)) /* interrupt not caused by RXF, return */

return;

CAN1RFLG 5 RXF; /* clear RXF flag */

tmp 5 CAN1IDAC & 0x07; /* extract filter hit info */

if (tmp 55 0) { /* filter 0 hit */