iPhone USB Charger to make or trouble-shoot

First, you need 4 resistors with these values: 2 of 33 kΩ, 1 of 47 kΩ and 1 of 22 kΩ.

Apple iPhone (1G, 3G, 3GS, 4) Dock connector
pinout

 

 

 

Pin	Signal	Description
1	GND	Ground (-), internally connected with Pin 2 on iPhone motherboard
2	GND	Audio & Video ground (-), internally connected with Pin 1 on iPod motherboard
3	Right	Line Out - R (+) (Audio output, right channel) . See also Apple iPhone headset  connector pinout
4	Left	Line Out - L(+) (Audio output, left channel)
5	Right In	Line In - R (+)
6	Left In	Line In - L (+)
8
9
10
11	GND	If connected to GND the iPhone sends audio signals through pin 3-4, otherwise it uses onboard speaker.
12	Tx	iPhone sending line, Serial TxD
13	Rx	iPhone receiving line, Serial RxD
14	RSVD	Reserved
15	GND	Ground (-), internally connected with pin 16 on iPhone motherboard
16	GND	USB GND (-), internally connected with pin 15 on iPhone motherboard
17	RSVD	Reserved
18	3.3V	3.3V Power (+) ?
19,20	+12V	Firewire Power 12 VDC (+)
21	Accessory Indicator/Serial enable	Different resistances indicate accessory type:   1kOhm - docking station, beeps when connected    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 charge an iPhone 3G / iPod Touch 2nd gen 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. 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.
28	TPB (+)	FireWire Data TPB (+)
29,30	GND	FireWire Ground (-)

Back side of dock connector;
 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30
 1 3 5 7 9 11 13 15 17 19 21 23 25 27 29

Pins 1,2 connected on motherboard.

Pins 15,16 connected on motherboard.

Pins 19,20 connected on motherboard.

Pins 29,30 connected on motherboard.

If you disassemble the original Apple iPhone dock connector cable


and look at the connector itself, on the back side, where it is soldered,
you

can see the number 1 and 30 (e.g. pin 1 and 30). In this description
NUMBERING

is INVERSED: pin 1 is pin 30 and pin 29 is pin 2, so, don't look at numbers
on

connector.

This device may be connected to the firewire computer port by straight


cable (TPB+/-, TPA +/- should be twisted pairs in cable). It seems there are


no file transfer allowed, but it can charge via this interface.