[geeks] Purely out of curiosity... USB with 5 pins?

[Jonathan C. Patschke]

On Fri, 4 Apr 2008, Alois Hammer wrote:

> I'm curious to know: why the proliferation of USB (especially MiniUSB)
> connectors with five pins?  Does the extra help coax more power out of
> uncooperative root ports?  All the root port pinouts I've seen are
> still four-pin, and I don't see references to "USB 2.1" anywhere...

My guess would be that the USB standards demand that the pin remain
disconnected.  Therefore, when using the port for non-USB things (like
plugging in a mobile phone charger) the extra pin can be used for
manufacturer-specific purposes (an additional power rail, thermal
feedback to the charger, etc.).

-- 
Jonathan Patschke | "There is no such thing as a short of reserves...
Elgin, TX         |  one bank can have a problem...the Fed can print
USA               |  money, there is no shortage."
.                 |     --Jim Glassman, US Economist, JPMorgan Chase