Bruce Gennette wrote, in part:
>[About TMR0]
>5 Each time it hits 0 it tries to set an interrupt flag.  The user must
>clear this flag manually.

What do you mean by "tries"? Am I missing something here? (Very
possible, I'm new to PICs! I love them though!).

>6 You may choose not to use interrupts, just manually examine the current
>value to find when it passes 0.

Someone correct me if I am wrong, but I think that even if interrupts
are disabled, the T0IF bit is still set when TMR0 cycles from 0x0FF
to 0. That is the easiest and most reliable way to check when TMR0
has finished, since checking TMR0 for 0 runs the risk that it might
increment to 1 just as you are testing it. The Microchip Mid-Range
Reference Manual suggests that you work around this potential
problem by checking if the TMR0 value is 3 or less using a subtract,
but I think checking the T0IF bit is faster and more elegant. I hope
the experts will correct me if I am wrong (I am new to PICs!).

>Set the prescaler to use by TMR0
>Set pre scaler to x1 <--- damn, not allowed, minimum is x2

No problem! If you assign the prescaler to the WDT (by putting a
1 in bit 3 (PSA) of the Option register), then the TMR0 is not
scaled at all, meaning 1:1 (or x1 in your notation). I think!
(Did I mention that I'm new to PICs?).

Michael V

Thank you for reading my little posting.


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