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-rw-r--r--doc/openocd.texi9
1 files changed, 6 insertions, 3 deletions
diff --git a/doc/openocd.texi b/doc/openocd.texi
index 9f2e8227..6d88d832 100644
--- a/doc/openocd.texi
+++ b/doc/openocd.texi
@@ -1509,9 +1509,12 @@ Tap Uses:
parameters'', the required parameters are:
@comment START REQUIRED
@itemize @bullet
-@item @b{-irlen NUMBER} - the length in bits of the instruction register
-@item @b{-ircapture NUMBER} - the ID code capture command.
-@item @b{-irmask NUMBER} - the corresponding mask for the ir register.
+@item @b{-irlen NUMBER} - the length in bits of the instruction register, mostly 4 or 5 bits.
+@item @b{-ircapture NUMBER} - the IDCODE capture command, usually 0x01.
+@item @b{-irmask NUMBER} - the corresponding mask for the IR register. For
+some devices, there are bits in the IR that aren't used. This lets you mask
+them off when doing comparisons. In general, this should just be all ones for
+the size of the IR.
@comment END REQUIRED
@end itemize
An example of a FOOBAR Tap