Jean-Yves wrote:
>
>> <snip>
>> >
>> >12C509s seemed a good value at aboout $3USD total.  But I don't see how to
>> >make them work now that I figured out they lack interrupts.  A 16C62 will
>>
>> You have an interrupt -> MCLR on pin 4!
>>
>        Is it possible to drive this Reset-interrupt pin by the timer (if
>you can afford an external Pin out to drive it ?)
>
>        Any experience on this topic ?
>

        No, a chip cannot drive it's own reset without additional hardware.
I was under the impression that the one '509 was to be used as a wakeup
timer for the other, so the easiest way to wakeup is by the master clear.
The unfortunate part with all the wakeups/powerups on these chips is that
there's the initial 300us time when all the pins are tristated. If you were
driving an output, this may cause problems.


        Jim

  Elm Electronics
  ICs for Experimenters
http://www.elmelectronics.com/