My Gta02s wont charge / chgena = 0 by default

Werner Almesberger werner at
Mon Jun 23 14:23:42 CEST 2008

Joerg Reisenweber wrote:
> No, don't think so. It's the manufacturer's way to say "set max voltage and 
> max current etc, before you even think about enabling charging).

Reality check: in the seven PCF50633 variants Philips have specified,
we have the following defaults:

Variant 1, 4, 9: 500mA, charger disabled
Variant 2, 3, 5: 500mA, charger enabled
Variant 7:       100mA, charger enabled

I just wish we had these three bits from variant 7 :) Even more, I
wish NXP had given their device a little EEPROM to provide the
default settings. (An MCU could help, but only once the system's
made it our of Standby, since I2C is only operating in Active.)

> When we've done this, manufacturer does us the favor to make this 
> state "sticky" so PMU will awake from backup-battery with whatever we decided 
> it should. And it should awake with charging nicely configured and enabled.

This only applies to bits that don't reset in Standby. E.g., the
current limit in MBCC7 resets in Standby, not NoPower. (All other
MBC settings reset in NoPower.)

> Yeah, but doesn't apply to our discussion here. We're talking about return 
> from low-bat / suspend, not initial wakeup from a drained backup-bat.

There's a catch though: if our solution misbehaves badly after
NoPower, it would mean that Neos would start to fail mysteriously
after some time, when the backup battery has gone bad (due to wear
or - much more likely self-discharge).

> We have proven we are able to come up from defaults - that's what every
> device is doing fist time it's powered up.

This first power-on at the factory may be different (*) from a
power-on after the device has spent half a year in some drawer,
with all batteries discharged.

(*) I don't know what power the fixture used at that point provides.
    In general, when bringing up virgin devices manually, there's a
    good battery in them.

Also, please bear in mind that the scenario Sean McNeil confirmed
is just one that includes settings you would encounter after

- Werner

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