On Thu, Mar 27, 2008 at 8:18 PM, joerg <[EMAIL PROTECTED]> wrote:
Alas there is *absolutely* *NO* way for NEO though to tell when your braindead
850mA charger will start to slowly melt down overnight when you set 1A charge
mode via applet. It's very unlikely there will ever be any trouble other than
very rare occasional broken chargers, but we just can't guarantee it's safe,
for nobody knows all the chargers in this world.
As a hacker poking around with prototype hardware, that's a fine
answer. For a mass market device, that's suicide. I understand that
the Neo can't make the determination, but in the long run I think that
Openmoko MUST. It is physically possible to charge the Neo at it's
full speed (because it happens with the USB charger) so therefore it
must be physically POSSIBLE to have an AC or DC based charger that
does the same thing without requiring a computer tether. If any
charger on the market can do this I think it would be simple enough
for Openmoko to "certify" that the MODEL (not each unit, of course) is
compatible and, unless it malfunctions, won't burst into flame.
If there exists no such device on the market then perhaps that needs
to be corrected either directly or indirectly. Put very simple "Car
charging is a very big deal". Assuming the first (certification) or
second (fabrication) options can't be met - drop the "fast charge" as
a feature since anyone unable to fast charge in their car will
consider their device "broken" at best or sold on a feature that
doesn't exist.
However it's not our fault when sth really bad is happening, for every
charger/host is supposed to be short-circuit safe (mustn't burn, otherwise
probably mustn't be sold),
I don't think anybody expects a certification of safety from Openmoko
(there are voluntary organizations like Underwriter's Laboratories
here in the US that will certify safety) for a product to go to market
and even if they DID nobody can rightly expect you'll certify that no
device will ever malfunction.
and it's the USER who has to think *before*
enabling 1A mode. Hey guys, when connecting your 110V device to a 230V outlet
in Europe, whom do you blame for the smoke?!
The "common user" mentality is one that has, IMO, bitten Free Software
repeatedly. As a serious (and non-belittling) thought exercise, how
many people here know what amperage their car charger pushes out? How
many people here have wives or mothers or nephews that know that
answer?
The average person buys a car charger because the box says "Compatible
with <model>". Some might not even go that far since a commonly held
assumption is that "if it fits in the hole, it will work". Yeah, kinda
stupid, but it's also pretty reasonable to expect that this WILL
happen. It's also reasonable to suspect that at least SOME people will
take that and have it reflect poorly on Openmoko even if the charger
was bought third party. It's sometimes easy to dismiss user stupidity
when you're writing code that you use and the only signs you see are a
ticking download counter or more hits in a server log, but this is
something that I think could directly relate to the ability to sell
SECOND units to people.
bottom line: USB is specified for 500mA at MAX, and even this needs
intelligent host (alias charger). Everything beyond has to have some
intelligence with it, either the one of the user not messing with chargemode,
or the one of OM-designers creating and checking for a proprietary way to
signal >500mA charger capabilities (=48k).
(PS: For the record: If i got this right, the 48k even means "I'm a charger
and I can do *2*(!)A", just GTA02 can't take more than 1A. This might change
for GTA0x!)
HTH
cheers
your friendly engineer jOERG
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