
Debug in depth
C-34
Copyright 2000 ARM Limited. All rights reserved.
ARM DDI 0165B
C.10.5
Debug control register
The debug control register is 6 bits wide. Writing control bits occurs during a register
write access (with the read/write bit HIGH). Reading control bits occurs during a
register read access (with the read/write bit LOW).
Figure C-10 shows the function of each bit in this register.
Figure C-10 Debug control register format
54
3
2
1
0
Embedded-ICE
disable
Monitor mode
enable
Single-step
INTDIS
DBGRQ
DBGACK
Table C-7 Debug control register bit functions
Bit
number
Name
Function
5Embedded-
ICE disable
Controls the address and data comparison logic contained within
the Embedded-ICE logic. When set to 1, the address and data
comparators are disabled. When set to 0, the address and data
comparators are enabled. You can use this bit to save power in a
system where the Embedded-ICE functionality is not required.
The reset state of this bit is 0 (comparators enabled). An extra
piece of logic initialized by debug reset ensures that the
Embedded-ICE logic is automatically disabled out of reset. This
extra logic is set by debug reset and is automatically reset on the
first access to scan chain 2.
4Monitor
mode
enable
Controls the selection between monitor mode debug (monitor
mode enable = 1) and halt mode debug. In monitor mode,
breakpoints and watchpoints cause Prefetch Aborts and Data
Aborts to be taken (respectively). At reset, the monitor mode
enable bit is set to 1.
3
Single-step
Controls the single-step hardware. This is explained in more
2
INTDIS
If bit 2 (INTDIS) is asserted, the interrupt signals to the
processor are inhibited. Table C-8 shows interrupt signal control.
1:0
DBGRQ,
DBGACK
These bits allow the values on DBGRQ and DBGACK to be
forced.