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authorntfreak <ntfreak@b42882b7-edfa-0310-969c-e2dbd0fdcd60>2009-01-08 11:46:55 +0000
committerntfreak <ntfreak@b42882b7-edfa-0310-969c-e2dbd0fdcd60>2009-01-08 11:46:55 +0000
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- a few more docs tweaks
git-svn-id: svn://svn.berlios.de/openocd/trunk@1306 b42882b7-edfa-0310-969c-e2dbd0fdcd60
Diffstat (limited to 'doc')
-rw-r--r--doc/openocd.texi35
1 files changed, 20 insertions, 15 deletions
diff --git a/doc/openocd.texi b/doc/openocd.texi
index dea01969..1866fa0e 100644
--- a/doc/openocd.texi
+++ b/doc/openocd.texi
@@ -3184,24 +3184,29 @@ halt
@*
In digital circuit design it is often refered to as ``clock
-syncronization'' the JTAG interface uses one clock (TCK or TCLK)
+synchronisation'' the JTAG interface uses one clock (TCK or TCLK)
operating at some speed, your target is operating at another. The two
-clocks are not syncronized, they are ``asynchronous''
+clocks are not synchronised, they are ``asynchronous''
-In order for the two to work together they must syncronize. Otherwise
+In order for the two to work together they must be synchronised. Otherwise
the two systems will get out of sync with each other and nothing will
-work. There are 2 basic options. @b{1.} use a special circuit or
-@b{2.} one clock must be some multile slower the the other.
+work. There are 2 basic options.
+@enumerate
+@item
+Use a special circuit.
+@item
+One clock must be some multiple slower the the other.
+@end enumerate
@b{Does this really matter?} For some chips and some situations, this
-is a non-issue (ie: A 500mhz ARM926) but for others - for example some
-ATMEL SAM7 and SAM9 chips start operation from reset at 32khz -
+is a non-issue (ie: A 500MHz ARM926) but for others - for example some
+ATMEL SAM7 and SAM9 chips start operation from reset at 32kHz -
program/enable the oscillators and eventually the main clock. It is in
those critical times you must slow the jtag clock to sometimes 1 to
-4khz.
+4kHz.
-Imagine debugging that 500mhz arm926 hand held battery powered device
-that ``deep sleeps'' at 32khz between every keystroke. It can be
+Imagine debugging that 500MHz ARM926 hand held battery powered device
+that ``deep sleeps'' at 32kHz between every keystroke. It can be
painful.
@b{Solution #1 - A special circuit}
@@ -3213,14 +3218,14 @@ The RTCK signal often found in some ARM chips is used to help with
this problem. ARM has a good description of the problem described at
this link: @url{http://www.arm.com/support/faqdev/4170.html} [checked
28/nov/2008]. Link title: ``How does the jtag synchronisation logic
-work? / how does adaptive clocking working?''.
+work? / how does adaptive clocking work?''.
The nice thing about adaptive clocking is that ``battery powered hand
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.
-@b{Solution #2 - Always works - but is slower}
+@b{Solution #2 - Always works - but may be slower}
Often this is a perfectly acceptable solution.
@@ -3230,7 +3235,7 @@ depending upon the chips on your board. @b{ARM Rule of thumb} Most ARM
based systems require an 8:1 division. @b{Xilinx Rule of thumb} is
1/12 the clock speed.
-Note: Many FTDI2232C based JTAG dongles are limited to 6mhz.
+Note: Many FTDI2232C based JTAG dongles are limited to 6MHz.
You can still debug the 'lower power' situations - you just need to
manually adjust the clock speed at every step. While painful and
@@ -3244,7 +3249,7 @@ this way.
To set the JTAG frequency use the command:
@example
- # Example: 1.234mhz
+ # Example: 1.234MHz
jtag_khz 1234
@end example
@@ -3390,7 +3395,7 @@ You can use the ``scan_chain'' command to verify and display the tap order.
Many newer devices have multiple JTAG taps. For example: ST
Microsystems STM32 chips have two taps, a ``boundary scan tap'' and
-``cortexM3'' tap. Example: The STM32 reference manual, Document ID:
+``CortexM3'' tap. Example: The STM32 reference manual, Document ID:
RM0008, Section 26.5, Figure 259, page 651/681, the ``TDI'' pin is
connected to the Boundary Scan Tap, which then connects to the
CortexM3 Tap, which then connects to the TDO pin.