Setting / checking fast charge in /sys/devices/platform/whatever

Al Johnson openmoko at
Tue Jul 15 00:17:03 CEST 2008

On Monday 14 July 2008, Stroller wrote:
> Hi there,
> It looks like my problem with SIM registration [1] may be easily
> solvable simply by trying a different SIM or reseating the current one.
> But because I'm fetishistic about following battery charging
> instructions I don't want to try this (which requires removing the
> battery) until the unit is fully charged.
> The wiki [2] says:
>    The battery can be charged using the provided charger (at 1000mA)
>    or from a powered USB port capable of providing 500mA worth of
>    current. Most computers will be able to charge the FreeRunner without
>    any problems.
>    Charging at 100mA takes 6-12 hours and at 500mA takes 1-2 hour
> I understood the provided charger was a dumb one and that - because
> the Freerunner is unable to communicate with it - an unpowered USB
> connection would be assumed, the Freerunner would act conservatively,
> only drawing 100mA.
> Which is correct, please?

The charger is dumb, but has a 47k resistor from the ID pin of the USB 
connector to ground. This allows the Freerunner to identify it as capable to 
provide 1000mA. See the USB Host section of: 

> I decided to try forcing the Freerunner to fast-charge, and a little
> Googling found me the CheckFastCharge-script on the Wiki [3].
> Reading I find that it checks '/sys/devices/
> platform/s3c2410-i2c/i2c-adapter/i2c-0/0-0008/chgmode' and that fast
> charging is indicated by "fast_cccv" there.
> Presumably this script was written for the Neo1973, however, or a
> different kernel, as on my Freerunner the location is '/sys/devices/
> platform/s3c2440-i2c/i2c-adapter/i2c-0/0-0073/chgmode' and it
> currently says "fast", not "fast_cccv" (or, for that matter, slow or
> anything like that).
> So is "fast" the correct syntax for the Freerunner's chgmode?
> Has it somehow detected that the charger is capable of 500+ mA?
> Or should I echo "fast_cccv" to that location?
> What are the correct '/sys/devices/platform/s3c2440-i2c/i2c-adapter/
> i2c-0/0-0073/chgmode' values for "slow" and no-charge for the
> Freerunner, please? (using the default factory image)
> Or is chgmode simply broken on the Freerunner's default factory image?
> TIA for any suggestions,
> Stroller.
> [1]
> [2]
> Getting_Started_with_your_Neo_FreeRunner#Charging_the_Neo_Freerunner
> [3]
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