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authordbrownell <dbrownell@b42882b7-edfa-0310-969c-e2dbd0fdcd60>2009-10-07 15:31:33 +0000
committerdbrownell <dbrownell@b42882b7-edfa-0310-969c-e2dbd0fdcd60>2009-10-07 15:31:33 +0000
commitb83d79a42f908d3860f06910fdec8fb4fc670e6c (patch)
tree5d679187b5e4a128b81db6a8bfc436b56885bfa6 /doc
parentdc871f422da8943de9eecaa163b4a5bf54460379 (diff)
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Updates for "reset_config":
- revert to previous default: don't talk JTAG during SRST - add "srst_nogates" flag, the converse of "srst_gates_jtag" - with no args, display the current configuration And update the User's Guide text with bullet lists to be a bit more clear. git-svn-id: svn://svn.berlios.de/openocd/trunk@2818 b42882b7-edfa-0310-969c-e2dbd0fdcd60
Diffstat (limited to 'doc')
-rw-r--r--doc/openocd.texi28
1 files changed, 22 insertions, 6 deletions
diff --git a/doc/openocd.texi b/doc/openocd.texi
index 8156de4d..11267fc0 100644
--- a/doc/openocd.texi
+++ b/doc/openocd.texi
@@ -2099,7 +2099,7 @@ nTRST (active-low JTAG TAP reset) before starting new JTAG operations.
@end deffn
@deffn {Command} reset_config mode_flag ...
-This command tells OpenOCD the reset configuration
+This command displays or modifies the reset configuration
of your combination of JTAG board and target in target
configuration scripts.
@@ -2113,7 +2113,9 @@ from a particular combination of interface and board.
with a board that only wires up SRST.)
The @var{mode_flag} options can be specified in any order, but only one
-of each type -- @var{signals}, @var{combination}, @var{trst_type},
+of each type -- @var{signals}, @var{combination},
+@var{gates},
+@var{trst_type},
and @var{srst_type} -- may be specified at a time.
If you don't provide a new value for a given type, its previous
value (perhaps the default) is unchanged.
@@ -2121,6 +2123,8 @@ For example, this means that you don't need to say anything at all about
TRST just to declare that if the JTAG adapter should want to drive SRST,
it must explicitly be driven high (@option{srst_push_pull}).
+@itemize
+@item
@var{signals} can specify which of the reset signals are connected.
For example, If the JTAG interface provides SRST, but the board doesn't
connect that signal properly, then OpenOCD can't use it.
@@ -2128,10 +2132,11 @@ Possible values are @option{none} (the default), @option{trst_only},
@option{srst_only} and @option{trst_and_srst}.
@quotation Tip
-If your board provides SRST or TRST through the JTAG connector,
+If your board provides SRST and/or TRST through the JTAG connector,
you must declare that or else those signals will not be used.
@end quotation
+@item
The @var{combination} is an optional value specifying broken reset
signal implementations.
The default behaviour if no option given is @option{separate},
@@ -2144,26 +2149,37 @@ haven't seen hardware with such a bug, and can be worked around).
@option{combined} implies both @option{srst_pulls_trst} and
@option{trst_pulls_srst}.
-@option{srst_gates_jtag} indicates that asserting SRST gates the
+@item
+The @var{gates} tokens control flags that describe some cases where
+JTAG may be unvailable during reset.
+@option{srst_gates_jtag} (default)
+indicates that asserting SRST gates the
JTAG clock. This means that no communication can happen on JTAG
while SRST is asserted.
+Its converse is @option{srst_nogate}, indicating that JTAG commands
+can safely be issued while SRST is active.
+@end itemize
The optional @var{trst_type} and @var{srst_type} parameters allow the
driver mode of each reset line to be specified. These values only affect
JTAG interfaces with support for different driver modes, like the Amontec
-JTAGkey and JTAGAccelerator. Also, they are necessarily ignored if the
+JTAGkey and JTAG Accelerator. Also, they are necessarily ignored if the
relevant signal (TRST or SRST) is not connected.
+@itemize
+@item
Possible @var{trst_type} driver modes for the test reset signal (TRST)
-are @option{trst_push_pull} (default) and @option{trst_open_drain}.
+are the default @option{trst_push_pull}, and @option{trst_open_drain}.
Most boards connect this signal to a pulldown, so the JTAG TAPs
never leave reset unless they are hooked up to a JTAG adapter.
+@item
Possible @var{srst_type} driver modes for the system reset signal (SRST)
are the default @option{srst_open_drain}, and @option{srst_push_pull}.
Most boards connect this signal to a pullup, and allow the
signal to be pulled low by various events including system
powerup and pressing a reset button.
+@end itemize
@end deffn