[Gta04-owner] charging gta04 on my bicycle

Andreas Kemnade andreas at kemnade.info
Fri Jul 11 18:37:56 CEST 2014


On Fri, 11 Jul 2014 08:55:10 +0200
"Dr. H. Nikolaus Schaller" <hns at goldelico.com> wrote:

> Hi,
> the charger is a little critical about the VBUS voltage. It reports an issue if >5.2 V and drops charging if <4.4 V.
> But charging is only (re)started if VBUS goes below ca. 1.5V.
> So there is a situation for VBUS voltages where it does not charge even if you have 5.0V.
> Andreas has modified things to make it work on a bike:
> http://www.ohsw.de/gta04-otg.pdf
> http://www.ohsw.de/gta04-bike.pdf
Just the most important things at a glance:
echo on >/sys/bus/platform/devices/twl4030_bci/lin
is the key to charge at a bike. That will give around 500mA.
Then it tries to charge with whatever voltage Vbus is. You should turn
that off again after cycling.
I did a lot of experiments with my bike+electronics. So you see a lot
of things in the slides which is not necessary for just charging the
gta04 with a hub dynamo. I started to cycle with a gta0X in the Summer
2008. So that presentation is a bit of a summary of all things I tried

btw: That photo with me and my bike near the north cape tunnel was also
taken by a swiss cyclist doing a long trip

One thing about airport security: In Stockholm-Skavsta I boarded a
plane with the electronics dismounted in 2008, In Trondheim (Norway) I
left the electronics at the bike (with the hub dynamo disconnected)
while boarding the plane in 2011. Both times no problems.

That is a good reminder to finally put my schematics online.

Andreas Kemnade
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