Functional Peripherals Registers
175
SLAU356I – March 2015 – Revised June 2019
Copyright © 2015–2019, Texas Instruments Incorporated
Cortex-M4F Peripherals
Table 2-93. DHCSR Register Field Descriptions (continued)
Bit
Field
Type
Reset
Description
5
C_SNAPSTALL
R/W
0h
If the core is stalled on a load/store operation the stall ceases and
the instruction is forced to complete. This enables Halting debug to
gain control of the core. It can only be set if: C_DEBUGEN = 1 and
C_HALT = 1. The core reads S_RETIRE_ST as 0. This indicates
that no instruction has advanced. This prevents misuse. The bus
state is Unpredictable when this is used. S_RETIRE can detect core
stalls on load/store operations.
4
RESERVED
R/W
0h
3
C_MASKINTS
R/W
0h
Mask interrupts when stepping or running in halted debug. Does not
affect NMI, which is not maskable. Must only be modified when the
processor is halted (S_HALT == 1). Also does not affect fault
exceptions and SVC caused by execution of the instructions.
CMASKINTS must be set or cleared before halt is released. This
means that the writes to set or clear C_MASKINTS and to set or
clear C_HALT must be separate.
2
C_STEP
R/W
0h
Steps the core in halted debug. When C_DEBUGEN = 0, this bit has
no effect. Must only be modified when the processor is halted
(S_HALT == 1).
1
C_HALT
R/W
0h
Halts the core. This bit is set automatically when the core Halts. For
example Breakpoint. This bit clears on core reset. This bit can only
be written if C_DEBUGEN is 1, otherwise it is ignored. When setting
this bit to 1, C_DEBUGEN must also be written to 1 in the same
value (value[1:0] is 2'b11). The core can halt itself, but only if
C_DEBUGEN is already 1 and only if it writes with b11).
0
C_DEBUGEN
R/W
0h
Enables debug. This can only be written by AHB-AP and not by the
core. It is ignored when written by the core, which cannot set or clear
it. The core must write a 1 to it when writing C_HALT to halt itself.