National CP3BT26 manual TSEG1, TSEG2, Rtr Ide, Xrtr

CP3BT26

TSEG1	The Time Segment	1 field configures the
	length of the Time Segment 1 (TSEG1). It is
	not recommended to configure the time seg-
	ment 1 to be smaller than 2 time quanta. (see
	Table 59).
	Table 59 Time Segment 1 Settings
	TSEG1[3:0]		Length of Time
			(TSEG1)
	0000		Not recommended
	0001		2 time quanta
	0010		3 time quanta
	0011		4 time quanta
	0100		5 time quanta
	0101		6 time quanta
	0110		7 time quanta
	0111		8 time quanta
	1000		9 time quanta
	1001		10 time quanta
	1010		11 time quanta
	1011		12 time quanta
	1100		13 time quanta
	1101		14 time quanta
	1110		15 time quanta
	1111		16 time quanta
TSEG2	The Time Segment 2 field specifies the num-
	ber of time quanta (tq) for phase segment 2
	(see Table 60).
	Table 60 Time Segment 2 Settings
	TSEG2		Length of TSEG2
	000		1 time quantum
	001		2 time quanta
	010		3 time quanta
	011		4 time quanta
	100		5 time quanta
	101		6 time quanta
	110		7 time quanta
	111		8 time quanta

19.10.8 Global Mask Register (GMSKB/GMSKX)

The GMSKB and GMSKX registers allow software to global- ly mask, or “don’t care” the incoming extended/standard identifier bits, RTR/XRTR and IDE. Throughout this docu- ment, the GMSKB and GMSKX 16-bit registers are refer- enced as a 32-bit register GMSK.

The following are the bits for the GMSKB register.

15	5	4	3	2	0
GM[28:18]		RTR	IDE		GM[17:15]
		0
		R/W

The following are the bits for the GMSKX register.

15	1	0
GM[14:0]		XRTR
0
R/W

For all GMSKB and GMSKX register bits, the following ap- plies:

0 – The incoming identifier bit must match the correspond- ing bit in the message buffer identifier register.

1 – Accept 1 or 0 (“don’t care”) in the incoming ID bit inde- pendent from the corresponding bit in the message buffer ID registers. The corresponding ID bit in the mes- sage buffer will be overwritten by the incoming identifier bits.

When an extended frame is received from the CAN bus, all GMSK bits GM[28:0], IDE, RTR, and XRTR are used to mask the incoming message. In this case, the RTR bit in the GMSK register corresponds to the SRR bit in the message. The XRTR bit in the GMSK register corresponds to the RTR bit in the message.

During the reception of standard frames only the GMSK bits GM[28:18], RTR, and IDE are used. In this case, the GM[28:18] bits in the GMSK register correspond to the ID[10:0] bits in the message.

Global Mask	GM[28:18]	RTR	IDE	GM[17:0]	XRTR
Standard	ID[10:0]	RTR	IDE	Unused
Frame
Extended	ID[28:18]	SRR	IDE	ID[17:0]	RTR
Frame

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