#qi-hardware IRC log for Wednesday, 2015-04-01

DocScrutinizer05((so they must be single-digit cents in the rest of the world)) rather like 3 digit cents07:54
DocScrutinizer05arossdotme: there is no such resistor to "put across USB socket", so also no value for it08:52
DocScrutinizer05arossdotme: and yes, the docs are charger amendment to USB spec08:53
DocScrutinizer05but you don't want to read those since they are obfuscated wording08:53
DocScrutinizer05http://en.wikipedia.org/wiki/USB#Power for a short introduction08:56
DocScrutinizer05http://web.archive.org/web/20140329080504/http://www.usb.org/developers/devclass_docs/batt_charging_1_1.zip for the gory details08:57
DocScrutinizer05http://www.instructables.com/id/Modify-a-cheap-USB-charger-to-feed-an-iPod-iPhone/ for *CHRAGER*, *NOT* device side08:59
DocScrutinizer05generally chargers are dumb PSU and don't need _anything_ to provide whatever they can09:00
DocScrutinizer05it's up to your device to *detect* the resistors in charger to determine how much power your device may draw from it09:01
DocScrutinizer05or you simply ignore all such detection hassly and draw as much as you need, hoping that the charger won't explode ;-)09:01
whitequarkin a charger you often short D+ D- to indicate that it's well09:23
whitequarka charger09:23
whitequarkthe device will then usually place no current limit and draw 2A or so09:23
whitequarktablets even 4A sometimes09:23
DocScrutinizer054A via USB? Duh!09:27
whitequarksome large 10" or such tablet09:28
whitequarkcrazy but they do it09:28
DocScrutinizer05generally it's correct, there are 3 ways a charger can signal it's a charger: ID pin resistor to GND, D+/- short, and a number of resistor networks on D+/- to signal several apple-compatible chargers of different power09:29
DocScrutinizer05a device however usually needs one particular of those 3 alternative/complementary methods09:29
DocScrutinizer05only a very few devices check for more than just one method09:30
DocScrutinizer05e.g. Neo900 will09:30
DocScrutinizer05it checks for all D+/- based signaling09:30
arossdotmearr ok, i see so in this case i don't need to do anything fancy.13:10
arossdotmethanks muchly13:10
arossdotmethe resistor across the data,id pins are for the devices sake and not for the charger... what was i thinking... silly me13:11
arossdotmebut thx for the links13:12
arossdotmei'll have a loot in a bit13:12
--- Thu Apr 2 201500:00

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