Weekly edition	Kernel	Security	Distributions	Contact Us	Search
Archives	Calendar	Subscribe	Write for LWN	LWN.net FAQ	Sponsors

Battery charging "logic"

Posted Oct 22, 2009 14:28 UTC (Thu) by forthy (guest, #1525)
In reply to: OMAP, N900 and openness by laf0rge
Parent article: Maemo Summit 2009: Fremantle, Harmattan, and N900

Having seen the data sheets of several battery charger chips for mobile phones, I can't see what's that fuzz about (the data sheets are available). These chips have an extremely simple interface: three logic pins, all open drain logic: enable, power present, charging. There's little possible magic behind driving these three pins.

What's more interesting is a charge tracking circuit - and the code behind that. That code might have patented algorithms inside, so it's probably not easy to release it.

(Log in to post comments)

Posted Oct 24, 2009 10:14 UTC (Sat) by nix (subscriber, #2304) [Link]

The people who sell those circuits also claim that they are protected for
health and safety reasons: if they released the code and someone changed
it and a battery exploded...

... and that's why nobody ever uses Linux or free software in
life-or-death situations. They rely on reliable code from vendors who can
be sued for endangering life and limb, like Microsoft.

(But perhaps that's not entirely 100% accurate.)

Battery charging "logic"

Posted Oct 24, 2009 21:11 UTC (Sat) by anselm (subscriber, #2796) [Link]

It turns out that the Microsoft EULA doesn't allow you to use Windows in life-or-death situations, such as nuclear plant or air traffic control. This tells us that Microsoft doesn't think their own code is good enough for these applications -- at least not to the point of putting their money on it.

On the other hand, nobody ever successfully sued Microsoft over a bug in their software.