HP 50G USB power & running faster - auto shift from 75Mhz to 203Mhz
pynnonen
ARM9's clock from 75Mhz to 203Mhz? When it is disconnnected, drop it
back down to 75Mhz. Also, many USB devices charge via the USB port, why
not do the same for the HP 50G?
Also, I called the HP Help Center, and they were not aware that you
could run the HP 50G from the USB. I even tried removing the batteries,
and it still worked.
If anyone from HP is a calculator engineer, please inform them of this
capability.
Is the HP 50G USB port High Speed(480Mbs) or Full Speed(12Mbs)?
Brion
I saw severel mentions of the ability to power the 50g from the USB
port, but when I tried to confirm that on the HP Calc web site or in
the two on-line manuals, there is no mention of it. If the calc could
also charge (NiMH) batteries from the USB port, I would buy it even
though I have an hp49g+. That may be too hard for them to do - most
devices I know of that charge their batteries from USB power are Li-ion
based.
Brion
The Maverick
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.
bokubob
connector on the end that is the same one that the 50G has on it. So,
if you just want a power supply, you could pick up one of those I
suppose (though I don't have a 50G to test this idea)
pynnonen wrote:
> Also, many USB devices charge via the USB port, why
> not do the same for the HP 50G?
If we're charging batteries with the usb port, then I suppose they
don't "need" to be AAA (though there are nice things about such
batteries) we could have a li-ion pack. With a li-ion pack, it
doesn't need to be so thick.... how about a flat, thin 50G the size of
a 42s?
Before we go on about how great AAAs are, consider all of the car and
portable chargers out there. For instance:
http://www.instructables.com/id/EGBQJPLCB2EP287KTZ/
-Jonathan
James M. Prange
> If the HP 50G can get its power from the USB, why not also kick up the
> ARM9's clock from 75Mhz to 203Mhz? When it is disconnnected, drop it
> back down to 75Mhz.
That's a good idea, if we assume that the *only* reason for
choosing to not run the processor at its highest possible speed is
to limit battery current.
Other possible considerations in choosing the processor speed
could include avoiding overheating, working reliably with other
hardware, such as SRAM and flash memory, and the correct speeds
for the communications ports.
I've read that the 49g+ (which implies the 50g as well) can work
at higher speeds, but what is the highest speed that it can
*reliably* work with, including at the environmental extremes?
Do the external communication ports work correctly when the
processor speed is increased?
Other than that, I'm not so sure that the operating system "knows"
where the power is coming from, only what the power supply voltage
is. The switch between drawing power from the battery and getting
it from the USB port could be entirely in hardware, without ever
telling the processor or operating system about it.
> Also, many USB devices charge via the USB port, why
> not do the same for the HP 50G?
That one's easy; other devices that use the USB port are designed
to use a particular rechargeable battery, but the 50g is (I
assume) designed to use non-rechargeable alkaline cells, although
various other batteries do work just fine with it. Designing it to
be rechargeable would mean designing it for a particular
rechargeable battery, and product safety liability issues would be
a consideration. I much prefer the flexibility of having the
option to use different kinds of batteries, and if I choose to use
a rechargeable battery, then simply use an external charger for it.
But although you can't charge the 50g's battery through the USB
port, I've read that the serial port connector includes a
connection directly to the battery, for the option of powering
anything that you choose to connect. You could connect a charger
(suitable for whatever rechargeable battery you happen to use)
through the serial port connector.
> Also, I called the HP Help Center, and they were not aware that you
> could run the HP 50G from the USB. I even tried removing the batteries,
> and it still worked.
>
> If anyone from HP is a calculator engineer, please inform them of this
> capability.
I agree, but I note that within large corporations, the various
departments don't always communicate very well. The "help
centers", those who write the documentation, the "web masters" who
post documentation and revised firmware and applications, and
marketing usually aren't as knowledgeable about the actual
products as we'd desire.
> Is the HP 50G USB port High Speed(480Mbs) or Full Speed(12Mbs)?
Good question; I don't know the answer. For all that I know, it
might even be Low Speed (1.5Mbps).
--
Regards,
James
Veli-Pekka Nousiainen
> If the HP 50G can get its power from the USB, why not also kick up the
> ARM9's clock from 75Mhz to 203Mhz? When it is disconnnected, drop it
> back down to 75Mhz.
Perhaps next model :-D
Currently the SRAM & LCD can't cope with that speed
Perhaps 120MHz if designed to do so
> 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
> Also, I called the HP Help Center, and they were not aware that you
> could run the HP 50G from the USB. I even tried removing the
> batteries, and it still worked.
>
> If anyone from HP is a calculator engineer, please inform them of this
> capability.
>
> Is the HP 50G USB port High Speed(480Mbs) or Full Speed(12Mbs)?
? It uses serial speed 115200, so slow mode is enough
I wonder if this could be speede up in the future
while keeping everything reliable
ROM upgrade speed could be different from I/O speed
waiting fo HP-51G ??
Joe Horn
> I'm not so sure that the operating system "knows" where the power
> is coming from, only what the power supply voltage is. The switch
> between drawing power from the battery and getting it from the USB
> port could be entirely in hardware, without ever telling the processor
> or operating system about it.
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.
-Joe-
Gene
Veli-Pekka Nousiainen wrote:
> > 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. All it would take is one explosion while
charging to have HP sued in today's lawyer-conscious society.
I'd be shocked if we ever saw the ability to charge through the USB
port.
Veli-Pekka Nousiainen
In good old days HP simply warned about using anything else
than official HP battery pack
My HP-41CV was powered by Alkalines, but the later HP-41CX using the Pack
Simply: HP releases Battery Pack for the HP 51G and allows loading via USB
(or better yet: the pack is Litium-Ion)
BTW
HP iPAQ machine have rechargeable batteries and no explosions!
Gene
Veli-Pekka Nousiainen wrote:
> In good old days HP simply warned about using anything else
> than official HP battery pack
> My HP-41CV was powered by Alkalines, but the later HP-41CX using the Pack
> Simply: HP releases Battery Pack for the HP 51G and allows loading via USB
> (or better yet: the pack is Litium-Ion)
> BTW
> HP iPAQ machine have rechargeable batteries and no explosions!
Gene: Yes, the good old days before lawyers started trying to rule the
world.
With the 41CX, you could not recharge N cells in the machine. It tood a
special battery pack. I dont' see any room in the 50g battery
compartment for that sort of pack.
And, about the iPAQ, not only does that increase the cost, the design
was probably created to detect what type of batteries are in there.
That (to my knowledge) was not the case with the product tree leading
to the 50g (48sx, 48gx, 49g, 49g+).
So, changing it now would cost $XXXX (whatever), would benefit a tiny
tiny portion of their users, and would potentially expose them to
lawsuits anyway. And, any time spent re-engineering the power circuits
of the 50g is time HP does not have to bring out the new HP41CX+++IIGX
machine I saw in a dream last week. Seriously, if HP spent 4-6 months
doing this, would it lead to even a blip increase in sales? No way.
I'd bet money this will never happen.
mats
>>> 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?
Veli-Pekka Nousiainen
According to Gene: NOT HP
According to Veli:
HP will introduce an iPAQ-calc combo
that uses USB charger & Lion-battery
David Boyd
@b28g2000cwb.googlegroups.com:
In the meantime, there are USB-powered battery chargers, vis:
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=7609958331
Not quite as handy, but fairly handy nonetheless.
--
Dave Boyd
"Sufficient unto the Dave is the evil thereof." MAT 6:34
Remove UCETRAP to reply
Veli-Pekka Nousiainen
X
> In the meantime, there are USB-powered battery chargers, vis:
>
> http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=7609958331
>
> Not quite as handy, but fairly handy nonetheless.
David was a king & man of God
Thanks, David!
John H Meyers
> 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).
[r->] [OFF]
Samuel Stearley
associated with the various chip selects ?