Intel 87C196CB, 8XC196NT Canstat, Busoff Warn Rxok Txok LEC2 LEC1 LEC0, LEC2 LEC1 LEC0 Error Type

CAN SERIAL COMMUNICATIONS CONTROLLER

CAN_STAT	Address:	1E01H
(87C196CB)	Reset State:	XXH

The CAN status (CAN_STAT) register reflects the current status of the CAN peripheral.

87C196CB

7

BUSOFF WARN — RXOK

0

TXOK LEC2 LEC1 LEC0

Bit	Bit				Function
Number	Mnemonic
7	BUSOFF	Bus-off Status
		The CAN peripheral sets this read-only bit to indicate that it has isolated
		itself from the CAN bus (floated the TX pin) because an error counter has
		reached 256. A bus-off recovery sequence clears this bit and clears the
		error counters. (See “Bus-off State” on page 7-41.)
6	WARN	Warning Status
		The CAN peripheral sets this read-only bit to indicate that an error counter
		has reached 96, indicating an abnormal rate of errors on the CAN bus.
5	—	Reserved. This bit is undefined.
4	RXOK	Reception Successful
		The CAN peripheral sets this bit to indicate that a message has been
		successfully received (error free, regardless of acknowledgment) since the
		bit was last cleared. Software must clear this bit when it services the
		interrupt.
3	TXOK	Transmission Successful
		The CAN peripheral sets this bit to indicate that a message has been
		successfully transmitted (error free and acknowledged by at least one
		other node) since the bit was last cleared. Software must clear this bit
		when it services the interrupt.
2:0	LEC2:0	Last Error Code
		This field indicates the error type of the first error that occurs in a message
		frame on the CAN bus. (“Error Detection and Management Logic” on page
		7-9 describes the error types.)
		LEC2 LEC1 LEC0 Error Type
		0	0	0	no error
		0	0	1	stuff error
		0	1	0	form error
		0	1	1	acknowledgment error
		1	0	0	bit 1 error
		1	0	1	bit 0 error
		1	1	0	CRC error
		1	1	1	unused

Figure 7-20. CAN Status (CAN_STAT) Register

If an individual message object caused the interrupt request (CAN_INT = 02–10H), software can read the associated message object control 0 register (Figure 7-21). The INT_PND bit-pair will be set, indicating that a receive or transmit interrupt request is pending

7-33