On Tue, Aug 26, 2008 at 8:23 PM, Spen <[EMAIL PROTECTED]> wrote:
>> >>
>> >> STR912 now uses RCLK if available.
>> >>
>> >
>> > Could i ask why? Because using rclk is slower.
>>
>> Is it?
>
> it has been on all the interfaces i have tested over the years.
>
> Even arm and segger mention this in their docs, if you have a fast jtag tool
> in theory it should be as close to the max possible clock. in practice using
> correctly configured jtag clock has always been quicker.

So for those interfaces where this *is* the case, then jtag_rclk does
not make sense and jtag_khz is still the way to go. For LPC2148
and STR912, they maxed out about the same frequency AFAICT.

I *suspect* that RCLK is more robust that eeking a few more
khz out of the communication line and a near top speed & robust
is better than something faster & potentially flaky as a default.

Again: you can override the behaviour of jtag_rclk easily enough.


-- 
Øyvind Harboe
http://www.zylin.com/zy1000.html
ARM7 ARM9 XScale Cortex
JTAG debugger and flash programmer
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