Quote:
Originally Posted by dhbailey
I certainly understand the "one cable" concept, and I agree wholeheartedly, but not only will all devices have to be redesigned so that they all use the same usb-mini connector, they'll also have to be redesigned electronically so they all use the same amount of current for the charging.
Or am I missing something -- do all USB-mini ports which charge share the same current requirements? So that I could charge my Zen mp3 player, which charges through the USB-mini port, using the same charger that I use for my Bluetooth earpiece, which also charges through the USB-mini-port? I've been leery of trying that, knowing that if the current doesn't match the requirement either the charger or the device could be ruined.
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USB pinout signals
USB is a serial bus. It uses 4 shielded wires: two for power (+5v & GND) and two for differential data signals (labelled as D+ and D- in pinout). NRZI (Non Return to Zero Invert) encoding scheme used to send data with a sync field to synchronise the host and receiver clocks. In USB data cable Data+ and Data- signals are transmitted on a twisted pair. No termination needed. Half-duplex differential signaling helps to combat the effects of electromagnetic noise on longer lines. Contrary to popular belief, D+ and D- operate together; they are not separate simplex connections.
This is true for USB A, B and mini, so what you get is the +5 volts, no matter what. The bad part about it is that the USB bus can only provide 500 mA, so if you have several devices in the same USB-hub for instance, then they all have to share the 500 mA, and thus, may not charge due to not delivering enough "juice"