Initializing the SJA1000

Do
	- Set RESET_REQUEST bit
	- Clear TEST_MODE bit
	- Write ACCEPTANCE CODE REGISTER
	- Write ACCEPTANCE MASK REGISTER
	- Write BUS TIMING REGISTER 0
	- Write BUS TIMING REGISTER 1
	- Write OUTPUT CONTROL REGISTER
	- Enable interrupt sources (bits 1..4 of CONTROL REGISTER)
	- Clear RESET_REQUEST bit
End

Interrupt processing of SJA1000

On interrupt do
	Copy INTERRUPT REGISTER into CPU memory
	(* Use only the copy to evaluate interrupt bits  during processing *)
	
	If WAKE_UP_INTERRUPT=1 then
		If CPU state = "Asleep" then
			(* Bus activated by external activity *)
			Awake CPU and process CAN datas
		Else
			(* GOTO SLEEP command was not accepted by SJA1000 *)
			Perform adequate processing
		Endif
	Endif

	If TRANSMIT_INTERRUPT=1 then
		Next CAN message can be written in TRANSMIT BUFFER
		Set TRANSMIT_REQUEST bit

		If ABORT_TRANSMISSION command requested
			If TRANMISSION_COMPLETE_STATUS=1 then
				(* Last CAN message transmitted. 
				ABORT TRANSMISSION command not processed *)
			Else
				(* Last CAN message transmission aborted.
				ABORT TRANSMISSION command processed *)
			Endif
		Endif
	Endif

	If RECEIVE_INTERRUPT=1 then
		Read RECEIVE BUFFER content and store it into CPU memory
		Set RELEASE RECEIVE BUFFER bit
		
		If OVERRUN_INTERRUPT=1 then
			(* Some CAN datas are lost ! *)
			Modify program to reduce processing time of CAN interrupts
			Set CLEAR OVERRUN bit
		Endif
	Endif

	If ERROR_INTERRUPT=1 then
		Read STATUS REGISTER
		If BUS_STATUS=1 ("on bus") then
			(* SJA1000 is again active on bus *)
			If ERROR_STATUS=0 then
				(* CAN bus is slightly disturbed *)
			Else
				(* CAN bus is highly disturbed *)
			Endif
		Else
			(* SJA1000 is disconnected from bus *)
			If bus connection is again needed
				Clear RESET_REQUEST bit
				(* SJA1000 waits for 128*11 recessive bits to reconnect 
*)
			Endif
		Endif
	Endif
End

'Polling' processing of SJA1000

Do
	Copy STATUS REGISTER into CPU memory
	(* Use only the copy to evaluate status bits during processing *)
	
	If TRANSMIT_BUFFER_ACCESS=1 then
		Next CAN message can be written in TRANSMIT BUFFER
		Set TRANSMIT_REQUEST bit

		If ABORT_TRANSMISSION command requested
			If TRANMISSION_COMPLETE_STATUS=1 then
				(* Last CAN message transmitted. 
				ABORT TRANSMISSION command not processed *)
			Else
				(* Last CAN message transmission aborted.
				ABORT TRANSMISSION command processed *)
			Endif
		Endif
	Endif

	If RECEIVE_BUFFER_STATUS=1 then
		Read RECEIVE BUFFER content and store it into CPU memory
		Set RELEASE RECEIVE BUFFER bit
		
		If OVERRUN_INTERRUPT=1 then
			(* Some CAN datas are lost ! *)
			Modify program to reduce processing time of CAN interrupts
			Set CLEAR OVERRUN bit
		Endif
	Endif

	If BUS_STATUS=1 ("on bus") then
		(* SJA1000 is again active on bus *)
		If ERROR_STATUS=0 then
			(* CAN bus is slightly disturbed *)
		Else
			(* CAN bus is highly disturbed *)
		Endif
	Else
		(* SJA1000 is disconnected from bus *)
		If bus connection is again needed
			Clear RESET_REQUEST bit
			(* SJA1000 waits for 128*11 recessive bits to reconnect *)
		Endif
	Endif
End