Oscillator startup time?

[lpcware]

Content originally posted in LPCWare by gbm on Mon Sep 20 09:32:00 MST 2010
LPC11xx docs state that in order to switch to a new clock source, the source must be running. How do I know that watchdog oscillator is running? I couldn't find a reference to any osc startup time or status flags in LPC11xx docs, but maybe I am not smart enough.
In my project I have a problem with switching WDT to WD OSC which I believe is not running and probably the switch does not occur - WDT still runs on IRC osc.

[lpcware]

Content originally posted in LPCWare by gbm on Tue Sep 21 02:16:37 MST 2010
We have a catch-22 here: ANY clock switch (MAINCLK, CLKOUT, WDTCLK) will succeed only if the target clock is running. So it is not possible to switch CLKOUT to WDT osc when WDT osc is not oscillating.
Same problem ocurs while trying to switch to IRC after deep sleep wakeup.

NXPers: please help! How do I know if a particular oscillator is running?

[lpcware]

Content originally posted in LPCWare by dbrunell on Mon Sep 20 22:17:48 MST 2010
Are you toggling the enable register (WDTCLKUEN)?  How about enabling the CLKOUT pin to be driven by the WDOSC, then setting a breakpoint just before you switch clocks?  You can check the WDOSC, then resume execution.