CAN Control Registers
1546
SPRUH22I – April 2012 – Revised November 2019
Copyright © 2012–2019, Texas Instruments Incorporated
M3 Controller Area Network (CAN)
Table 23-5. CAN Control Register (CAN CTL) Field Descriptions (continued)
Bit
Name
Value
Description
3
EIE
Error Interrupt Enable
0
Disabled - PER, BOff and EWarn bits cannot generate an interrupt.
1
Enabled - PER, BOff and EWarn bits can generate an interrupt at CAN0INT line and affect the
Interrupt Register.
2
SIE
Status Change Interrupt Enable
0
Disabled - WakeUpPnd, RxOk, TxOk and LEC bits cannot generate an interrupt.
1
Enabled - WakeUpPnd, RxOk, TxOk and LEC can generate an interrupt at CAN0INT line and affect
the Interrupt Register.
1
IE0
Interrupt line 0 Enable
0
Disabled - Module Interrupt CAN0INT is always low.
1
Enabled - Interrupts will assert line CAN0INT to one; line remains active until pending interrupts are
processed.
0
Init
Initialization mode bit. This bit may be set by software, a hardware reset, or the bus-off condition.
0
Normal operation.
1
Initialization mode is entered.
NOTE:
The Bus-Off recovery sequence (see CAN Specification Rev. 2.0) cannot be shortened by
setting or resetting Init bit. If the module goes Bus-Off, it will automatically set the Init bit and
stop all bus activities. When the Init bit is cleared by the application again, the module will
then wait for 129 occurrences of Bus Idle (129 * 11 consecutive recessive bits) before
resuming normal operation. At the end of the Bus-Off recovery sequence, the error counters
will be reset. After the Init bit is reset, each time when a sequence of 11 recessive bits is
monitored, a Bit0 Error code is written to the Error and Status Register, enabling the CPU to
check whether the CAN bus is stuck at dominant or continuously disturbed, and to monitor
the proceeding of the Bus-Off recovery sequence.
23.15.2 Error and Status Register (CAN ES)
The Error and Status register (CAN ES) is shown and described in the figure and table below.
Figure 23-20. Error and Status Register (CAN ES) [offset = 0x04]
31
16
Reserved
R-0
15
10
9
8
7
6
5
4
3
2
0
Reserved
Wake
UpPnd
PER
BOff
EWarn
EPass
RxOK
TxOK
LEC
R-0
R/C-0
R/C-0
R-0
R-0
R-0
R/C-0
R/C-0
R/S-111
LEGEND: R = Read; S = Set by Read; C = Clear by Read; -
n
= value after reset
Table 23-6. Error and Status Register Field Descriptions
Bit
Field
Value
Description
31-10
Reserved
Reserved
9
WakeUpPnd
Wake Up Pending This bit can be used by the CPU to identify the CAN as the source to wake up
the system.
0
No Wake Up is requested by CAN.
1
Wake up is requested. CAN has initiated a wake up of the system due to dominant CAN bus while
module power down. This bit will be reset if Error and Status Register is read.