37.1 Tx Buffer Element 0

Table 37-88. Register Bit Attribute Legend
Symbol	Description	Symbol	Description	Symbol	Description
R	Readable bit	HC	Cleared by Hardware	(Grey cell)	Unimplemented
W	Writable bit	HS	Set by Hardware	X	Bit is unknown at Reset
K	Write to clear	S	Software settable bit	—	—

Name:	T0
Offset:	0x000
Reset:	0x00000000
Property:	-


Bit	31	30	29	28	27	26	25	24
	ESI	XTD	RTR	ID[28:24]
Access	R/W	R/W	R/W	R/W	R/W	R/W	R/W	R/W
Reset	0	0	0	0	0	0	0	0


Bit	23	22	21	20	19	18	17	16
	ID[23:16]
Access	R/W	R/W	R/W	R/W	R/W	R/W	R/W	R/W
Reset	0	0	0	0	0	0	0	0


Bit	15	14	13	12	11	10	9	8
	ID[15:8]
Access	R/W	R/W	R/W	R/W	R/W	R/W	R/W	R/W
Reset	0	0	0	0	0	0	0	0


Bit	7	6	5	4	3	2	1	0
	ID[7:0]
Access	R/W	R/W	R/W	R/W	R/W	R/W	R/W	R/W
Reset	0	0	0	0	0	0	0	0

Bit 31 – ESI Error State Indicator

Note: The ESI bit of the transmit buffer is OR’ed with the error passive flag to decide the value of the ESI bit in the transmitted FD frame. As required by the CAN FD protocol specification, an error active node may optionally transmit the ESI bit recessive, but an error passive node will always transmit the ESI bit recessive.

Value	Description
0	ESI bit in CAN FD format depends only on error passive flag.
1	ESI bit in CAN FD format transmitted recessive.

Bit 30 – XTD Extended Identifier

Value	Description
0	11-bit standard identifier.
1	29-bit extended identifier.

Bit 29 – RTR Remote Transmission Request

Value	Description
0	Transmit data frame.
1	Transmit remote frame

Bits 28:0 – ID[28:0] Identifier

Standard or extended identifier depending on bit XTD. A standard identifier is stored into ID[28:18].