David Brownell <david-b@pacbell.net>:
Minor updates to the text about reset configuration: - Mention a new point that it interacts with JTAG routers; - Talk about a "user" config file not a "system" one; - Remove text from the "reset_config" description; instead, cross-reference the more extensive text earlier. git-svn-id: svn://svn.berlios.de/openocd/trunk@2243 b42882b7-edfa-0310-969c-e2dbd0fdcd60
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@ -1911,6 +1911,7 @@ configuration. This can also be quite confusing.
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Resets also interact with @var{reset-init} event handlers,
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Resets also interact with @var{reset-init} event handlers,
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which do things like setting up clocks and DRAM, and
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which do things like setting up clocks and DRAM, and
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JTAG clock rates. (@xref{JTAG Speed}.)
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JTAG clock rates. (@xref{JTAG Speed}.)
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They can also interact with JTAG routers.
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Please see the various board files for examples.
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Please see the various board files for examples.
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@quotation Note
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@quotation Note
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@ -1919,11 +1920,12 @@ Reset configuration touches several things at once.
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Normally the board configuration file
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Normally the board configuration file
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should define it and assume that the JTAG adapter supports
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should define it and assume that the JTAG adapter supports
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everything that's wired up to the board's JTAG connector.
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everything that's wired up to the board's JTAG connector.
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However, the target configuration file could also make note
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However, the target configuration file could also make note
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of something the silicon vendor has done inside the chip,
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of something the silicon vendor has done inside the chip,
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which will be true for most (or all) boards using that chip.
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which will be true for most (or all) boards using that chip.
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And when the JTAG adapter doesn't support everything, the
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And when the JTAG adapter doesn't support everything, the
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system configuration file will need to override parts of
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user configuration file will need to override parts of
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the reset configuration provided by other files.
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the reset configuration provided by other files.
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@end quotation
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@end quotation
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@ -1967,6 +1969,7 @@ and @command{reset init} commands; after @command{reset init} a
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board-specific script might do things like setting up DRAM.
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board-specific script might do things like setting up DRAM.
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(@xref{Reset Command}.)
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(@xref{Reset Command}.)
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@anchor{SRST and TRST Issues}
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@section SRST and TRST Issues
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@section SRST and TRST Issues
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Because SRST and TRST are hardware signals, they can have a
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Because SRST and TRST are hardware signals, they can have a
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@ -1979,9 +1982,11 @@ common issues are:
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SRST or TRST to the JTAG connector. Some JTAG adapters don't
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SRST or TRST to the JTAG connector. Some JTAG adapters don't
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support such signals even if they are wired up.
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support such signals even if they are wired up.
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Use the @command{reset_config} @var{signals} options to say
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Use the @command{reset_config} @var{signals} options to say
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when one of those signals is not connected.
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when either of those signals is not connected.
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When SRST is not available, your code might not be able to rely
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When SRST is not available, your code might not be able to rely
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on controllers having been fully reset during code startup.
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on controllers having been fully reset during code startup.
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Missing TRST is not a problem, since JTAG level resets can
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be triggered using with TMS signaling.
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@item @emph{Signals shorted} ... Sometimes a chip, board, or
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@item @emph{Signals shorted} ... Sometimes a chip, board, or
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adapter will connect SRST to TRST, instead of keeping them separate.
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adapter will connect SRST to TRST, instead of keeping them separate.
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@ -2051,17 +2056,14 @@ This command tells OpenOCD the reset configuration
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of your combination of JTAG board and target in target
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of your combination of JTAG board and target in target
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configuration scripts.
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configuration scripts.
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If you have an interface that does not support SRST and
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Information earlier in this section describes the kind of problems
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TRST(unlikely), then you may be able to work around that
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the command is intended to address (@pxref{SRST and TRST Issues}).
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problem by using a reset_config command to override any
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As a rule this command belongs only in board config files,
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settings in the target configuration script.
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describing issues like @emph{board doesn't connect TRST};
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or in user config files, addressing limitations derived
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SRST and TRST has a fairly well understood definition and
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from a particular combination of interface and board.
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behaviour in the JTAG specification, but vendors take
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(An unlikely example would be using a TRST-only adapter
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liberties to achieve various more or less clearly understood
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with a board that only wires up SRST.)
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goals. Sometimes documentation is available, other times it
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is not. OpenOCD has the reset_config command to allow OpenOCD
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to deal with the various common cases.
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The @var{mode_flag} options can be specified in any order, but only one
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The @var{mode_flag} options can be specified in any order, but only one
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of each type -- @var{signals}, @var{combination}, @var{trst_type},
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of each type -- @var{signals}, @var{combination}, @var{trst_type},
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