CAN Arbitration

#define CAN_PRIORITY_1				31
#define CAN_PRIORITY_2				30
#define CAN_PRIORITY_3				29
#define CAN_PRIORITY_4				28
#define CAN_PRIORITY_LO				0


#define BRAIN_INNER_VOL			64  //Lowest active CAN address
#define IAZ_BRAIN_ENC			65



void init_mailbox(void)
{
    mailboxCana(CAN_MAILBOX_4, CAN_DIR_RX, IAZ_BRAIN_ENC, CAN_8BYTE, CAN_NO_MASK, CAN_PRIORITY_LO);
	// And others
		
    mailboxCana(CAN_MAILBOX_21, CAN_DIR_TX, BRAIN_INNER_VOL, CAN_8BYTE, CAN_NO_MASK, CAN_PRIORITY_1);
	// And others

}





void init_cana(void)
{
	InitECanaGpio();							// Init IO for CAN_A module
	InitECana(); 								// Initialize eCAN-A module 
	
	ECanaRegs.CANRMP.all = 0xFFFFFFFF;			// Clear the received message pending bits
	ECanaRegs.CANTA.all = 0xFFFFFFFF;   		// Clear all transmit Ack (TAn) bits

	// DSP CAN port_a  MailBox and Bus Error Interrupt Initialisation 
	EALLOW;

	ECanaRegs.CANOPC.all = 0xFFFFFFFF;			// Set over write protect.

	ECanaRegs.CANGIM.all = 0x00000000;			// No interrupts enabled.

	ECanaRegs.CANMIM.all = 0x00000000;			// Disable Mailbox Interrupt for all 32 Mailboxes. 

	ECanaRegs.CANMIL.all = 0x00000000;			// Enable Mailbox interrupt on INT0 line when set to 0 
												// Enable Mailbox interrupt on INT1 line when set to 1 
	EDIS;
}




main()
{

	//extract from 1kHz loop
	ClearDebugOutput();							// port pin 

	cana_tx(BRAIN_INNER_VOL, &data);			

	SetDebugOutput();							// port pin 

}



void cana_tx(Uint16 message_id, CAN_DATA *tx_data)
{
	union CANTA_REG can_ta_shadow;
	union CANTRS_REG can_trs_shadow;

	switch(message_id)
	{

		// ******* Simple tx method version
		case BRAIN_INNER_VOL:
			if(ECanaRegs.CANTRS.bit.TRS21 == 0){	// Check mailbox is empty
				ECanaMboxes.MBOX21.MDL.all  = tx_data->can.longs.value1;		// Load first Long value
				ECanaMboxes.MBOX21.MDH.all  = tx_data->can.longs.value2;		// Load second Long value
				ECanaRegs.CANTRS.bit.TRS21 = 1;
			}
			break;


		// ******* Ref tx method as per TI examples
		case BRAIN_INNER_VOL:
			if(ECanaRegs.CANTRS.bit.TRS21 == 0){	// Check mailbox is empty
				ECanaMboxes.MBOX21.MDL.all  = tx_data->can.longs.value1;		// Load first Long value
				ECanaMboxes.MBOX21.MDH.all  = tx_data->can.longs.value2;		// Load second Long value

				can_trs_shadow.all = ECanaRegs.CANTRS.all;
				can_trs_shadow.bit.TRS21 = 1;
				ECanaRegs.CANTRS.all = can_trs_shadow.all;

			   do
				{
				   can_ta_shadow.all = ECanaRegs.CANTA.all;
				} while(can_ta_shadow.bit.TA21 == 0 );   // Wait for TAxx bit to be set..

			   can_ta_shadow.all = 0;
			   can_ta_shadow.bit.TA21 = 1;     	         // Clear TAxx
			   ECanaRegs.CANTA.all = can_ta_shadow.all;

			}
			break;

			
		default:
			if(ECanaRegs.CANTRS.bit.TRS31 == 0){	// Check mailbox is empty
				ECanaMboxes.MBOX31.MDL.all  = tx_data->can.longs.value1;			// Load first float value
				ECanaMboxes.MBOX31.MDH.all  = tx_data->can.longs.value2;			// Load second float value
				mailboxCana(CAN_MAILBOX_31, CAN_DIR_TX, message_id, CAN_8BYTE, CAN_NO_MASK, CAN_PRIORITY_LO);
				ECanaRegs.CANTRS.bit.TRS31 = 1;
			}
			break;
	}
}