Thread: Jolla hardware compatibility
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joerg_rw is offline joerg_rw
2013-12-27 , 12:12
Posts: 2,222 | Thanked: 12,651 times | Joined on Mar 2010 @ SOL 3
#19
Originally Posted by aegis View Post
Nokia themselves also ditched OMTP in the latest Lumias.
Nope, they did for their first lumias, the recent ones reportedly implement a dual-standard that automatically switches between OMTP and the insane "US standard"
Originally Posted by aegis View Post
The USB charging standard states that the two middle pins in the connectiin have to have a resistor connected or just shorted. This is what Nokia followed in the N9, N900 etc. Apple on the other hand decided to put a voltage across the two middle pins to tell it's products if the charger is compatible. Most 3rd party chargers follow the Apple rules. You can buy adapters that fit inline converting to the USB standard on ebay.

It's kind of sad that the standards were rolled over by the Apple accessory market but on a practical basis great that Jolla have realised which way the wind has blown.
Yes, one of the official USB standards as defined in charging amendment is to short the D+/- lines.
And according to
Code:
IroN900:~# cat /sys/devices/platform/musb_hdrc/charger
1
when attaching the Jolla charger to flawlessly charging N900 this is exactly what this charger does.
Also Jollaphone is charging happily from standard Nokia charger.
So maybe Jollaphone knows about the resistor voltage divider thing as used by Apple, but for sure they are using the "Nokia" standard by default.
OTOH it seems most aftermarket USB PSU simply don't connect the D+/- lines at all, they simply leave them open. So maybe it's iPhone that knows how to charge at max 500mA from arbitrary chargers, ignoring the USB specs. And there's no such thing like a wind blowing a particular direction?

/j
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Last edited by joerg_rw; 2013-12-27 at 12:46.
 

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