Re: 50g USB power. Is it normal for calc to reset?

Scotty wrote:
Is it something wrong with my unit? Or, is this something that
everyone experiences?


Something similar happens to me, although I seem to have a wimpy USB
hub that cannot supply enough power for the 50g to run reliably in
anything other than idle mode. It works fine when connected directly
to the computer though.

It appears that when the calculator is drawing USB power, it is unable
to quickly enough switch back to battery power with a relatively
gradual drop in power to its USB connection. However, when you
physically plug in and remove the USB cable, all is fine - no
warm-start. Either there is a mechanical switch (very doubtful) that
signals when a cable is plugged in or out, similar to the crude
AC-Adapter plugs that have such a mechanism, or the calculator responds
instantly to the sudden and immediate drop in USB power when the cable
is unplugged and switches back to its batteries without missing a beat.

I suspect that there is a voltage threshold set in the hardware
(firmware adjustable hopefully?) where the calculator switches back to
batteries and that a restart of your computer, where the USB voltage
drop is relatively gradually perhaps, and a drop in output of my wimpy
USB hub is not enough to trip the calculator back to using batteries
but, in both cases, there is not enough power to run the 50g reliably,
hence the warm-start (reboot).

All this is speculation on my part of course, however it sounds
plausible... to me at least! Personally I find the 50g's behavior,
with regards to how it draws power from USB, to be very badly
implemented - a power drop should not cause it to reboot! Well, not
unless its batteries are nearly exhausted of course.

As I had mentioned, I really hope that this behavior can somehow be
fixed with a firmware update.

Regards,
Mike Mander

.

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