From: Veli-Pekka Nousiainen on 11 Oct 2006 12:55
>>>> Also, many USB devices charge via the USB port,
>>>> why not do the same for the HP 50G?
>>> 1) safety
>>> 2) cost will go higher because of testing
>>> - nice idea though
>> Gene: HP does not do this, probably for liability reasons. Consumers
>> could put in all sorts of batteries, alkaline, NIMH and Nicad all in
>> the same set. It would add a great amount of expense to have the 50g
>> know what type was in there.
> Doing a little web search brings up this one: "Charging Batteries from
> USB" (http://www.maxim-ic.com/appnotes.cfm/an_pk/3607) and it doesn't
> seem to be that expensive. And they say (somewhere in the middle of
> the text): "In the DS2712, this difference in voltage is used to
> distinguish between NiMH cells and alkaline cells. If an alkaline
> cell is detected, the DS2712 will not charge it."
> Who's going to give it a try?
According to Gene: NOT HP
According to Veli:
HP will introduce an iPAQ-calc combo
that uses USB charger & Lion-battery
From: John H Meyers on 11 Oct 2006 17:45
On Wed, 11 Oct 2006 05:33:00 -0500, Joe Horn wrote:
> The OS knows, since the "ON-F, 8" battery test displays whether the
> machine is running off batts or USB power. The display changes
> instantly between "Battery Normal" and "USB Power" (or something like
> that) when a powered USB cable is plugged in or removed.
> Anybody know the entry point for testing whether the power is coming
> from the USB port? It'd be useful in long-running programs, rather
> than constantly testing the low-bat status.
The ARM OS knows, but the Saturn OS may not [until HPGCC adds a test];
also, I believe it was you who first reported the "brown out bug"
(in which no power switch is made at all if USB power
ramps down slowly, by which time even the Saturn OS
may have a clue, and presumably should indicate something).
From: Samuel Stearley on 23 Oct 2006 22:11
Out of curiosity did you ever try playing with the wait states
associated with the various chip selects ?
The Maverick wrote:
> pynnonen wrote:
> > If the HP 50G can get its power from the USB, why not also kick up the
> > ARM9's clock from 75Mhz to 203Mhz?
> Because you can't clock the memory reliably at that speed. I did a
> variety of tests using one of the overclock utilities a few months ago
> ... the highest speeds that were reliable didn't actually make much
> difference to the calculation speeds.
> In the end I just went back to good old 75 MHz.