The iPod docking connector is a standard feature of almost all Apple portable devices such as iPods, iPads and iPhones. This 30-pin connector allows a variety of peripherals to interface with the iPod. I am going to take a look at some of the signals that are transmitted via this connector to giove you an idea about how universal Apple’s devices are.
The iPod connector has 30 pins which are arranged in a row. The most basic signals are: USB Ground, USB Data+, USB Data- and USB Voltage (5 Volts). Interfacing with these few signals allows charging the iPod as well as exchanging data. A USB cable which connects the iPod with a PC or charging adapter typically only uses these 4 signals. In case of a charger, the USB Data signals are pulled to 2 Volts or 2.8 Volts in order to allow the iPod to charge. Also, the voltage on these signals determines the charge rate. If both signals are held at 2 Volts then a 0.5 A charge rate will be set. Otherwise a 1 A charge rate is set.
Additional signals on the dock connector are used by the ipod docking station from Amphony and include: audio line out left/right, Firewire signals, Video in/out and an accessory detect signal to tell the iPod what type of accessory is connected. Also, there are serial signals to run the Apple protocol.