From Xmultiple Engineering Dept.

The term Pinout used In electronics is a cross-reference between the contacts, or pins, of an electrical connector, and their functions.

Purpose
The functions of contacts in electrical connectors, be they power- or signaling-related, must be specified in order for connectors to be interchangeable. When connected, each contact of a connector must mate with the contact on the other connector that has the same function. If contacts of disparate functions are allowed to make contact, the connection may fail and damage may result. Therefore, pinouts are a vital reference when building and testing connectors, cables, and adapters.

Terminology
While one usage of the word pin is to refer to electrical contacts of, specifically, the male gender, its usage in pinout does not imply gender: the contact-to-function cross-reference for a connector that has only female, socket contacts is still called a pinout.

Representation
The pinout can typically be shown as a table or diagram, though it is necessary to clarify how to view the diagram, stating if it shows the backside of the connector (where wires are attached) or the "mating face" of the connector. Published pinouts, which are particularly important when different manufacturers want to interconnect their products using open standards, are typically provided by the connector or equipment manufacturer. Some pinouts are provided by 3rd parties since some connectors are not well documented by the manufacturer.

While repairing electronic devices, an electronics technician uses electronic test equipment to "pin out" each component on a PCB. The technician probes each pin of the component in turn, comparing the expected signal on each pin to the actual signal on that pin.

Some Pinout Examples are shown below.

Five (5) Pin Mini-USB Female Jack

Comparison Below Between Standard, Mini-USB and Micro-USB

 

Pin-Outs for Mini-USB and Micro-USB Jack

Pin	Name	Cable Color	Description
1	VCC	Red	+5 VDC
2	D-	White	Data -
3	D+	Green	Data +
X			This pin may be connected to GND for cable detection in some cases.
4	GND	Black	Ground

 

 

Connector pinout for: Apple iPod - iPhone dock

The Apple iPhone/iPod 30 pin connector is used on the dock station for iPod and iPhone and on many of the iPod and iPhone models. This connector is available in all Apple iPod MP3 player (iPod 1G, 2G, 3G, 4G, 5G and Nano).

This connector is used on iPod (starting from 3rd generation) and iPhone. It is used to connect the iPod or iPhone to various devices: PC (via USB or FireWire IEEE1394), audio amplifier, serial device (controlled via the Apple Accessory Protocol).

Pin	Signal	Description
1	GND	Ground (-), internally connected with Pin 2 on iPod motherboard
2	GND	Audio and Video ground (-), internally connected with Pin 2 on iPod motherboard
3	Right	Line Out - R (+) (Audio output, right channel)
4	Left	Line Out - L(+) (Audio output, left channel)
5	Right In	Line In - R (+)
6	Left In	Line In - L (+)
8	Video Out	Composite video output (only when the slideshow mode is active on iPod Photo)
9	S-Video Chrominance output	for iPod Color, Photo only
10	S-Video Luminance output	for iPod Color, Photo only
11	GND	Serial GND
12	Tx	iPod sending line, Serial TxD
13	Rx	iPod receiving line, Serial RxD
14	NC
15	GND	Ground (-), internally connected with pin 16 on iPod motherboard
16	GND	USB GND (-), internally connected with pin 15 on iPod motherboard
17	NC
18	3.3V	3.3V Power (+) Stepped up to provide +5 VDC to USB on iPod Camera Connector. If iPod is put to sleep while Camera Connector is present, +5 VDC at this pin slowly drains back to 0 VDC.
19,20	+12V	Firewire Power 12 VDC (+)
21	Accessory Indicator/Serial enable	Different resistances indicate accessory type: 1KOhm - iPod docking station, beeps when connected 10KOhm - Takes some iPods into photo import mode 68kOhm - makes iPhone 3g send audio through line-out without any messages 500KOhm - related to serial communication / used to enable serial communications Used in Dension Ice Link Plus car interface 1MOhm - Belkin auto adaptor, iPod shuts down automatically when power disconnected Connecting pin 21 to ground with a 1MOhm resistor does stop the iPod when power (i.e. Firewire-12V) is cut. Looks to be that when this pin is grounded it closes a switch so that on loss of power the IPod shuts off. Dock has the same Resistor.
22	TPA (-)	FireWire Data TPA (-)
23	5 VDC (+)	USB Power 5 VDC (+)
24	TPA (+)	FireWire Data TPA (+)
25	Data (-)	USB Data (-)
26	TPB (-)	FireWire Data TPB (-)
27	Data (+)	USB Data (+) Pins 25 and 27 may be used in different manner. To force the iPod 5G to charge in any case, when 'USB Power 5 VDC' (pin 23) is fed, 25 must be connected to 5V through a 10KOhm resistor, and 27 must be connected to the Ground (for example: pin 1) with a 10KOhm resistor.
28	TPB (+)	FireWire Data TPB (+)
29,30	GND	FireWire Ground (-)