On Wednesday 13 June 2007 06:10, Jinx wrote:
> > What is not perfectly clear is if the "Timer1 oacillator"
> > actualy is the *same* osc as "LFINTOSC".
> >
> > It's also not clear if they with "internal oscillator"
> > in section 6.4 means "HFINTOSC" (which *I* think) or
> > something else.
>
> The internal oscillator appears to be selectable between
> HF and LF. Both are distinct from the T1OSC pins and
> oscillator (Fig 4.1), so I'd say you could use T1OSC with
> either HF or LF


I'm looking at section 4.1 (Clock sources) and the associated diagram (Figure 
4-1).  There does seem to be a clear distinction between HFINTOSC and 
LFINTOSC.  The thing is that LFINTOSC has a separate output path to the LCD, 
PWRT, WDT, FSCM, but not to Timer 1.  That's fine, since that's an INTERNAL 
low-freq oscillator.  So the LP oscillator is clearly something else -- 
specifically a low-power mode of the external oscillator.  I'm just putting 
this here to be clear/explicit.

At the top of Fig 4-1 is the external oscillator.  Here, it goes to the same 
mux that the HFINTOSC goes to, and I don't see a separate path for it to feed 
Timer 1.  Now Figure 6-1 shows that external oscillator going to the same 
mux, and then going to the Timer1 module -- AFTER the mux.  This implies (or 
states) to me that Timer1 would be clocked from either the internal or 
external oscillator and the same mux selection would determine the 
microcontroller system clock source.  So it seems like I cannot do this.

Sigh.  I think it's time I whip out a breadboard to find out for sure.

Cheers,
-Neil.

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