38.13.1 CxCON

CAN FD Control Register

Note:

The individual bytes in this multibyte register can be accessed with the following register names:
- CxCONT: Accesses the top byte CON[31:24]
- CxCONU: Accesses the upper byte CON[23:16]
- CxCONH: Accesses the high byte CON[15:8]
- CxCONL: Accesses the low byte CON[7:0]
These bits can only be modified in Configuration mode (OPMOD[2:0] = 100).

Name:	CxCON
Address:	0x0100


Bit	31	30	29	28	27	26	25	24
	TXBWS[3:0]				ABAT	REQOP[2:0]
Access	R/W	R/W	R/W	R/W	S/HC	R/W	R/W	R/W
Reset	0	0	0	0	0	1	0	0


Bit	23	22	21	20	19	18	17	16
	OPMOD[2:0]			TXQEN	STEF	SERRLOM	ESIGM	RTXAT
Access	R	R	R	R/W	R/W	R/W	R/W	R/W
Reset	1	0	0	1	1	0	0	0


Bit	15	14	13	12	11	10	9	8
	ON		SIDL	BRSDIS	BUSY	WFT[1:0]		WAKFIL
Access	R/W		R/W	R/W	R	R/W	R/W	R/W
Reset	0		0	0	0	1	1	1


Bit	7	6	5	4	3	2	1	0
	CLKSEL	PXEDIS	ISOCRCEN	DNCNT[4:0]
Access	R/W	R/W	R/W	R/W	R/W	R/W	R/W	R/W
Reset	0	1	1	0	0	0	0	0

Bits 31:28 – TXBWS[3:0] Transmit Bandwidth Sharing

Delay between two consecutive transmissions (in arbitration bit times)

Value	Description
1111-1100	4096
1011	2048
1010	1024
1001	512
1000	256
0111	128
0110	64
0101	32
0100	16
0011	8
0010	4
0001	2
0000	No delay

Bit 27 – ABAT Abort All Pending Transmissions

Value	Description
1	Signals all transmit buffers to abort transmission
0	Module will clear this bit when all transmissions are aborted

Bits 26:24 – REQOP[2:0] Request Operation Mode

Value	Description
111	Sets Restricted Operation mode
110	Sets Normal CAN 2.0 mode; error frames on CAN FD frames
101	Sets External Loopback mode
100	Sets Configuration mode
011	Sets Listen Only mode
010	Sets Internal Loopback mode
001	Sets Disable mode
000	Sets Normal CAN FD mode; supports mixing of full CAN FD and Classic CAN 2.0 frames

Bits 23:21 – OPMOD[2:0] Operation Mode Status

Value	Description
111	Module is in Restricted Operation mode
110	Module is in Normal CAN 2.0 mode; error frames on CAN FD frames
101	Module is in External Loopback mode
100	Module is in Configuration mode
011	Module is in Listen Only mode
010	Module is in Internal Loopback mode
001	Module is in Disable mode
000	Module is in Normal CAN FD mode; supports mixing of full CAN FD and Classic CAN 2.0 frames

Bit 20 – TXQEN Enable Transmit Queue⁽²⁾

Value	Description
1	Enables TXQ and reserves space in RAM
0	Does not reserve space in RAM for TXQ

Bit 19 – STEF Store in Transmit Event FIFO⁽²⁾

Value	Description
1	Saves transmitted messages in TEF
0	Does not save transmitted messages in TEF

Bit 18 – SERRLOM Transition to Listen Only Mode on System Error⁽²⁾

Value	Description
1	Transitions to Listen Only mode on System Error
0	Transitions to Restricted Operation mode on System Error

Bit 17 – ESIGM Transmit ESI in Gateway Mode⁽²⁾

Value	Description
1	ESI is transmitted as recessive when the ESI of message is high or CAN controller is error passive
0	ESI reflects error status of the CAN controller

Bit 16 – RTXAT Restrict Retransmission Attempts⁽²⁾

Value	Description
1	Restricted retransmissions attempts, uses TXAT[1:0]
0	Unlimited number of retransmission attempts, TXAT[1:0] bits will be ignored

Bit 15 – ON CAN Enable

Value	Description
1	CAN module is enabled
0	CAN module is disabled

Bit 13 – SIDL CAN stop in Idle mode

Value	Description
1	Stops module operation in Idle mode
0	Does not stop module operation in Idle mode

Bit 12 – BRSDIS Bit Rate Switching (BRS) Disable

Value	Description
1	Bit rate switching is disabled, regardless of BRS in the transmit message object
0	Bit rate switching depends on the BRS of the transmit message object

Bit 11 – BUSY CAN Module is Busy

Value	Description
1	The CAN module is active
0	The CAN module is inactive

Bits 10:9 – WFT[1:0] Selectable Wake-up Filter Time

Value	Description
11	T11 Filter
10	T10 Filter
01	T01 Filter
00	T00 Filter

Bit 8 – WAKFIL Enable CAN Bus Line Wake-up Filter⁽²⁾

Value	Description
1	Uses CAN bus line filter for wake-up
0	CAN bus line filter is not used for wake-up

Bit 7 – CLKSEL CAN Module Clock Source Select⁽²⁾

Value	Description
1	CAN module is run from EXTCLK
0	CAN module is run from system clock

Bit 6 – PXEDIS Protocol Exception Event Detection Disabled⁽²⁾

A recessive “reserved bit” following a recessive FDF bit is called a “Protocol Exception”

Value	Description
1	Protocol exception is treated as a form error
0	If a protocol exception is detected, CAN will enter the Bus Integrating state

Bit 5 – ISOCRCEN Enable ISO CRC in CAN FD Frames⁽²⁾

Value	Description
1	Includes stuff bit count in CRC field and uses nonzero CRC initialization vector
0	Does not include stuff bit count in CRC field and uses CRC initialization vector with all zeroes

Bits 4:0 – DNCNT[4:0] DeviceNet™ Filter Bit Number (see Filtering on Data Bytes and Table 38-9 for more details

Value	Description
11111-10011	Invalid selection (compares up to 18 bits of data with EIDx)
10010	Compares up to Data Byte 2, bit 6 with EID17
10001	Compares up to Data byte 2, bit 7 with EID16
...	...
00010	Compares up to Data byte 0 bit 6 with EID1
00001	Compares up to Data byte 0 bit 7 with EID0
00000	Does not compare data bytes

The individual bytes in this multibyte register can be accessed with the following register names: CxCONT: Accesses the top byte CON[31:24] CxCONU: Accesses the upper byte CON[23:16] CxCONH: Accesses the high byte CON[15:8] CxCONL: Accesses the low byte CON[7:0] These bits can only be modified in Configuration mode (OPMOD[2:0] = 100).

38.13.1 CxCON

Bits 31:28 – TXBWS[3:0] Transmit Bandwidth Sharing

Bit 27 – ABAT Abort All Pending Transmissions

Bits 26:24 – REQOP[2:0] Request Operation Mode

Bits 23:21 – OPMOD[2:0] Operation Mode Status

Bit 20 – TXQEN Enable Transmit Queue(2)

Bit 19 – STEF Store in Transmit Event FIFO(2)

Bit 18 – SERRLOM Transition to Listen Only Mode on System Error(2)

Bit 17 – ESIGM Transmit ESI in Gateway Mode(2)

Bit 16 – RTXAT Restrict Retransmission Attempts(2)