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| -rw-r--r-- | doc/openocd.texi | 12 |
1 files changed, 12 insertions, 0 deletions
diff --git a/doc/openocd.texi b/doc/openocd.texi index 5537ba80..3a7538ee 100644 --- a/doc/openocd.texi +++ b/doc/openocd.texi @@ -5661,6 +5661,18 @@ held device example'' - the adaptiveness works perfectly all the time. One can set a break point or halt the system in the deep power down code, slow step out until the system speeds up. +Note that adaptive clocking may also need to work at the board level, +when a board-level scan chain has multiple chips. +Parallel clock voting schemes are good way to implement this, +both within and between chips, and can easily be implemented +with a CPLD. +It's not difficult to have logic fan a module's input TCK signal out +to each TAP in the scan chain, and then wait until each TAP's RTCK comes +back with the right polarity before changing the output RTCK signal. +Texas Instruments makes some clock voting logic available +for free (with no support) in VHDL form; see +@url{http://tiexpressdsp.com/index.php/Adaptive_Clocking} + @b{Solution #2 - Always works - but may be slower} Often this is a perfectly acceptable solution. |