main.c

MICROCHIP J1939实例代码

/*
Example 3b

This example shows what the receiving node for Example 3a should
look like, using the same concept as Example 2 of using interrupts to check for a message to light an LED and to send a message if a button
is pressed.  Note that three basic changes are required:
- it must accept the Commanded Address message (Application Maestro)
- it must have a CA_AcceptCommandedAddress function
- it must call J1939_Poll during the main loop, even though interrupts
  are being used.
The rest of the code is identical.  The change of address will be handled in the background. 

Application Maestro should be run with the following options changed
from their default values (in addition to NAME, Address, and bit rate
values): 

Commanded Address Message Accepted - Yes
*/

#include <p18cxxx.h>
#include "j1939.h"

J1939_MESSAGE Msg;

// Define some arbitrary values.  They must agree with the other node's
// values.

#define OTHER_NODE		129
#define TURN_ON_LED		92	
#define TURN_OFF_LED		94	
#define MAIN_LOOP_TIME_IN_MICROSECONDS 100

BOOL CA_AcceptCommandedAddress( void )
{
	return 1;
}

void InterruptHandlerLow (void);

//--------------------------------------------------------------------
// Low priority interrupt vector

#pragma code InterruptVectorLow = 0x0018
void InterruptVectorLow( void )
{
  _asm
    goto InterruptHandlerLow 
  _endasm
}

//--------------------------------------------------------------------
// Low priority interrupt routine

#pragma code
#pragma interruptlow InterruptHandlerLow

void InterruptHandlerLow( void )
{
	if (PIR3 != 0x00)
		J1939_ISR();
}

//--------------------------------------------------------------------

void main( void )
{
	unsigned char	LastSwitch = 1;
	unsigned char	CurrentSwitch;

	TRISBbits.TRISB4 = 1;			// Switch pin
	TRISD = 0;							// LED pins
	LATD = 0;							// Turn off LED

	J1939_Initialization( TRUE );
   INTCONbits.PEIE = 1;		// Enable peripheral interrupts
   INTCONbits.GIE = 1;		// Enable global interrupts

	// Wait for address contention to time out
	while (J1939_Flags.WaitingForAddressClaimContention)
		J1939_Poll(5);

	// Now we know our address should be good, so start checking for
	// messages and switches.

	while (1)
	{
		CurrentSwitch = PORTBbits.RB4;
		if (LastSwitch != CurrentSwitch)
		{
			Msg.DataPage				= 0;
			Msg.Priority				= J1939_CONTROL_PRIORITY;
			Msg.DestinationAddress	= OTHER_NODE;
			Msg.DataLength				= 0;
			if (CurrentSwitch == 0)
				Msg.PDUFormat = TURN_ON_LED;
			else
				Msg.PDUFormat = TURN_OFF_LED;
			while (J1939_EnqueueMessage( &Msg ) != RC_SUCCESS);
			LastSwitch = CurrentSwitch;
		}

		while (RXQueueCount > 0)
		{
			J1939_DequeueMessage( &Msg );
			if (Msg.PDUFormat == TURN_ON_LED)
				LATDbits.LATD0 = 1;
			else if (Msg.PDUFormat == TURN_OFF_LED)
				LATDbits.LATD0 = 0;
		}

		// We need to call J1939_Poll since we can accept the 
		// Commanded Address message.  Now the time value passed in
		// is important.
		J1939_Poll( MAIN_LOOP_TIME_IN_MICROSECONDS );
	}
}