Apple iPod, iPhone (2g, 3g), iPad Dock connector pinout

Pin	Signal	Description	Apple pin numbering*
1	GND	Ground (-), internally connected with Pin 2 on iPod motherboard	30
2	GND	Audio & Video ground (-), internally connected with Pin 1 on iPod motherboard	29
3	Right	Line Out - R (+) (Audio output, right channel)	28
4	Left	Line Out - L(+) (Audio output, left channel)	27
5	Right In	Line In - R (+)	26
6	Left In	Line In - L (+)	25
7	?		24
8	Video Out	Composite video output (only when slideshow active on iPod Photo) or Component Video Pb	23
9	S-Video Chrominance output	for iPod Color, Photo only or Component Video Y	22
10	S-Video Luminance output	for iPod Color, Photo only or Component Video Pr	21
11	AUDIO_SW	If connected to GND the iPhone sends audio signals through pin 3-4, otherwise it uses onboard speaker.	20
12	Tx	ipod sending line, Serial TxD	19
13	Rx	ipod receiving line, Serial RxD	18
14	RSVD	Reserved	17
15	GND	Ground (-), internally connected with pin 16 on iPod motherboard	16
16	GND	USB GND (-), internally connected with pin 15 on iPod motherboard	15
17	RSVD	Reserved	14
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.	13
19,20	+12V	Firewire Power 12 VDC (+)	11,12
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 6.8 kΩ - Serial port mode. Pin 11-13 are TTL level. Requires MAX232 chip to convert to RS232 levels. 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.	10
22	TPA (-)	FireWire Data TPA (-)	9
23	5 VDC (+)	USB Power 5 VDC (+)	8
24	TPA (+)	FireWire Data TPA (+)	7
25	Data (-)	USB Data (-)	6
26	TPB (-)	FireWire Data TPB (-)	5
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. iPod 5G can also be forced to charge by attaching the data + and the data - pins to the 5v via a 10k Ohm resistor ( BOTH PINS) and connecting pin 16 to the 5v (ground). (Confirmed working with iPod 5G 20GB). This provides 500mA of current for charging. For quicker charing, up to 1A, see below. To charge an iPhone, 3G, 3GS, 4 / iPod Touch, 2nd gen, 3rd, 4th or Ipod Classic (6th Gen), usb data- (25) should be at 2.8v, usb data+(27) should be at 2.0v. This can be done with a few simple resistors: 33k to +5v (23) and 22k to gnd(16) to obtain 2v and 33k to +5v and 47k to gnd to obtain 2.8v. This is a notification to the iphone that it is connected to the external charger and may drain amps from the usb. To charge iPod Nano pins 25 and 27 should be tied together and then connected to a 10K ohm resistor, and the other side of this resistors then needs to be connected to 5v power. It's also possible to charge the iPod's or iPhone's battery to make use the of internal +3.3v output (18) terminal to connect the USB Data + (27) thru a 47k ohms resistor and the USB Data- (25) thru a 47k resistor to the USB Power source +5v (23).  This way the USB function is still useable for normal operations and makes it easier the fit in a plug. The resistors are not to critical 2x 150k's still work. Added correction: iPod 2.1A charger advertises 2.8V on D+ and 2.0V on D-.  Tying either wire to 5V could damage the target - use resistors tied to 5.1V and ground to be safe.	4
28	TPB (+)	FireWire Data TPB (+)	3
29,30	GND	FireWire Ground (-)	1,2