Please let me know if I make some type of technical mistake in terminology. My topic revolves around USB connectors.
I have become aware of most of the issues surrounding the USB connector but there are some gray areas that I'd appreciate filling in by individuals that have more experience in the specifics. If there is a source that will describe all the assumptions that I'm making below, please provide that link or title of the source.
Areas and what I'm not so sure of:
1. I know that some types have 4 contacts and some types have 5 contacts. When there is only 4 is the missing one a power contact? In the case of the other contacts, do they always follow a convention of use in the same order?
2. Adapters must follow the corresponding corded connectors so that the flow-through will be compatible of course. Are there any surprises to that rule?
3. I believe that the contacts of USB connectors usually carry minimal voltage and amperage. Is the voltage usually 12VDC or below, and what is the usual maximum for amperage that is conveyed before burn out?
My specific need is for a CORD that is approximately 2-3 feet and has a FEMALE USB MICRO- B connector on one end and MALE USB MICRO-B connector on the other end. I have been searching the usual places that might be successful, but I'm not finding it. I have even asked for help and coming up with answers that are not showing brilliance. If not a single cord, then an ADAPTER that has a FEMALE USB TYPE-A connector to a MALE USB MICRO-B connector in the same adapter. I have a cord that I can use with this adapter and then I'm all good.
Best Answer
The 4 contacts found on type A and type B connectors are Power, Ground, Data+, and Data-. Power is at +5V, signaling is at 3.3V; the USB spec for cable length is such that these voltages will not drop beyond a certain value given the resistance of the wires.
The 5th conductor found on mini- and micro-USB connectors is the ID pin; it is either left floating or tied to ground via a resistor. It signals to the device what is at the other end of the cable; if floating then the other side is considered a USB host, whereas various resistances indicate presence of a charger or a media or communications device, or that the device plugged in should act as a OTG host (0ohms).
The physical pins have a specific order that is defined in the USB spec.