ARM Architecture Reference Manual ARMv7-A and ARMv7-R edition

A.1.1 Authentication signals
DBGEN, NIDEN, SPIDEN and SPNIDEN are the authentication signals.
Recommended External Debug Interface
DBGROMADDR[31:12] In v7 only ROM Table physical address DBGROMADDR and
DBGROMADDRV In v7 only ROM Table physical address
valid
NIDEN and SPNIDEN can be omitted if no non-invasive debug features are implemented.
SPIDEN and SPNIDEN can be omitted if Security Extensions are not implemented.
When DBGEN is LOW, indicating that debug is disabled:
Halting debug events are ignored
except for ignoring Halting debug events, the processor behaves as if DBGDSCR[15:14] == 0b00,
meaning that Monitor debug-mode and Halting debug-mode are both disabled. For more information,
see Debug Status and Control Register (DBGDSCR) on page C10-10.
For details of how these signals control enabling of invasive and non-invasive debug see Chapter C2
Invasive Debug Authentication and Chapter C7 Non-invasive Debug Authentication.
Note
The v7 Debug architecture authentication signal interface described here is compatible with the CoreSight
architecture requirements for the authentication interface of a debug component. However the CoreSight
architecture places additional requirements on other components in the system. For more information, see
the CoreSight Architecture Specification.
SPIDEN also controls permissions in Debug state. For details see Privilege in Debug state on page C5-13.
See also Authentication Status Register (DBGAUTHSTATUS) on page C10-96.
DBGROMADDRV on
page AppxA-10
DBGSELFADDR[31:12] In v7 only Debug self-address offset DBGSELFADDR and
DBGSELFADDRV In v7 only Debug self-address offset
valid
Table A-1 Miscellaneous debug signals (continued)
Name Direction Versions Description Section
DBGSELFADDRV on
page AppxA-10
DBGSWENABLE In v7 only Debug software access enable DBGSWENABLE on
page AppxA-11
PRESETDBGn In v7 only Debug logic reset PRESETDBGn on
page AppxA-12
ARM DDI 0406B Copyright © 1996-1998, 2000, 2004-2008 ARM Limited. All rights reserved. AppxA-3