Lpc2000

The 'max TCK=1/6 MCLK if RTCK not used' rule only appears to apply if 
the core is not in a debug state.

If the core is placed in a debug state, such as at a breakpoint,
there is no system clock to syncronise with!

While in a debug state JTAG will need to execute some one-at-a-time 
piped instructions at system speed before returning straight into a 
debug state (explained in prior posting). This may be an issue if
JTAG is polling for a return to debug state. However there is a hell 
a lot work carried out by JTAG debuggers outside this.

John Heenan




--- In lpc2000@yahoogroups.com, "John Heenan" <l10@a...> wrote:
> --- In lpc2000@yahoogroups.com, "Paul Curtis" <plc@r...> wrote:

> > Try this link.  http://www.arm.com/support/faqip/3732.html.  
> Extracting
> > the relevent details, "If the RTCK output is not used, it is 
> required
> > that TCK is running at a maximum of 1/6th the system clock 
> frequency if
> 
> Suppose RTCK is used then the limitation does not apply.
> 
> Suppose the system clock frequency is 60Mhz. Then TCK maximum is 
> 10Mhz if RTCK output is not taken advantage of. 
> 
>