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authorDavid Brownell <dbrownell@users.sourceforge.net>2009-11-05 11:31:32 -0800
committerDavid Brownell <dbrownell@users.sourceforge.net>2009-11-05 11:31:32 -0800
commitafed39c0fe20bffcf0f289e59e80ab9d6bb40a91 (patch)
tree4eff38b57bd0d4497b20c63aff86d8ab41397295
parent98788d7a75b4321c96845a8fbf814f254a6cf153 (diff)
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User's Guide: TAP setup tweakage
Highlight that the "-expected-id" probably comes from vendor documentation, and that it *should* be used where possible. Don't use ircapture/irmask in examples, to help discourage use of those params when they're not required. Explain a bit better about why/when those params get used. Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
-rw-r--r--doc/openocd.texi20
1 files changed, 14 insertions, 6 deletions
diff --git a/doc/openocd.texi b/doc/openocd.texi
index 2108f8e5..2ddcd041 100644
--- a/doc/openocd.texi
+++ b/doc/openocd.texi
@@ -1339,8 +1339,7 @@ The config file for the Atmel AT91SAM7X256
looks (in part) like this:
@example
-jtag newtap $_CHIPNAME cpu -irlen 4 -ircapture 0x1 -irmask 0xf \
- -expected-id $_CPUTAPID
+jtag newtap $_CHIPNAME cpu -irlen 4 -expected-id $_CPUTAPID
@end example
A board with two such at91sam7 chips would be able
@@ -2496,7 +2495,7 @@ requires explicit configuration of all TAP devices using
A command like this would declare one tap and name it @code{chip1.cpu}:
@example
-jtag newtap chip1 cpu -irlen 7 -ircapture 0x01 -irmask 0x55
+jtag newtap chip1 cpu -irlen 4 -expected-id 0x3ba00477
@end example
Each target configuration file lists the TAPs provided
@@ -2641,13 +2640,21 @@ These codes are not required by all JTAG devices.
ID code could appear (for example, multiple versions).
Specify @var{number} as zero to suppress warnings about IDCODE
values that were found but not included in the list.
+
+Provide this value if at all possible, since it lets OpenOCD
+tell when the scan chain it sees isn't right. These values
+are provided in vendors' chip documentation, usually a technical
+reference manual. Sometimes you may need to probe the JTAG
+hardware to find these values.
+@xref{Autoprobing}.
@item @code{-ircapture} @var{NUMBER}
@*The bit pattern loaded by the TAP into the JTAG shift register
on entry to the @sc{ircapture} state, such as 0x01.
JTAG requires the two LSBs of this value to be 01.
By default, @code{-ircapture} and @code{-irmask} are set
-up to verify that two-bit value; but you may provide
-additional bits, if you know them.
+up to verify that two-bit value. You may provide
+additional bits, if you know them, or indicate that
+a TAP doesn't conform to the JTAG specification.
@item @code{-irmask} @var{NUMBER}
@*A mask used with @code{-ircapture}
to verify that instruction scans work correctly.
@@ -6149,12 +6156,13 @@ to execute before they take effect.
@end deffn
@c tms_sequence (short|long)
-@c ... temporary, debug-only, probably gone before 0.2 ships
+@c ... temporary, debug-only, other than USBprog bug workaround...
@deffn Command {verify_ircapture} (@option{enable}|@option{disable})
Verify values captured during @sc{ircapture} and returned
during IR scans. Default is enabled, but this can be
overridden by @command{verify_jtag}.
+This flag is ignored when validating JTAG chain configuration.
@end deffn
@deffn Command {verify_jtag} (@option{enable}|@option{disable})