Debug/Suspend Mode
1079
SPNU503C – March 2018
Copyright © 2018, Texas Instruments Incorporated
Controller Area Network (DCAN) Module
23.16 Debug/Suspend Mode
When the CPU is halted during debug, all DCAN registers are visible and can be inspected and modified
by the CPU.
In addition, the Message RAM is directly memory-mapped as described in
The CAN controller provides two options for entering the debug/suspend state. The options are controlled
by the IDS bit in the CAN Control Register (DCAN CTL). By default, when IDS is 0, the DCAN controller
completes any active transfers on the CAN bus and waits until the bus is idle before halting. When IDS is
1, the DCAN halts immediately as soon as the CPU is halted.
The InitDbg bit in DCAN CTL register indicates when the DCAN controller has actually entered the
debug/suspend state.
NOTE:
During Debug/Suspend Mode, the Message RAM cannot be accessed via the IFx register
sets.
Writing to control registers in debug/suspend mode may influence the CAN state machine
and further message handling.
For debug support, the auto clear functionality of the following DCAN registers is disabled:
•
Error and Status Register (clear of status flags by read)
•
IF1/IF2 Command Registers (clear of DMA Active flag by read-write)
23.17 DCAN Control Registers
lists the control registers of the DCAN. After hardware reset, the registers of the DCAN hold
the values shown in the register descriptions. The base address for the control registers is FFF7 DC00h
for DCAN1, FFF7 DE00h for DCAN2, and FFF7 E000h for DCAN3.
Additionally, the Bus-Off state is reset and the CAN_TX pin is set to recessive (HIGH). The Init bit in the
CAN Control Register is set to enable the software initialization. The DCAN will not influence the CAN bus
until the CPU resets Init to 0.
Table 23-6. DCAN Control Registers
Offset
Acronym
Register Description
Section
00h
DCAN CTL
CAN Control Register
04h
DCAN ES
Error and Status Register
08h
DCAN ERRC
Error Counter Register
0Ch
DCAN BTR
Bit Timing Register
10h
DCAN INT
Interrupt Register
14h
DCAN TEST
Test Register
1Ch
DCAN PERR
Parity Error Code Register
20h
DCAN REL
Core Release Register
80h
DCAN ABOTR
Auto-Bus-On Time Register
84h
DCAN TXRQX
Transmission Request X Register
88h
DCAN TXRQ12
Transmission Request 12 Register
8Ch
DCAN TXRQ34
Transmission Request 34 Register
90h
DCAN TXRQ56
Transmission Request 56 Register
94h
DCAN TXRQ78
Transmission Request 78 Register
98h
DCAN NWDATX
New Data X Register
9Ch
DCAN NWDAT12
New Data 12 Register
A0h
DCAN NWDAT34
New Data 34 Register
A4h
DCAN NWDAT56
New Data 56 Register
A8h
DCAN NWDAT78
New Data 78 Register