I am in middle on trying to assemble a kegbot
and I am going to be using an Arduino to communicate with two Swiss flow sensors to monitor beer. I am also going to be interfacing a iPod Touch 2G through a protoshield to the Arduino. I have spent the past few days researching iDevice charging, and I feel I have a good understanding of the topic, and I also feel I have a basic understanding of power supplies, and what the Arduino is capable of.
Basically I would like to be able to charge the iPod Touch 2G from the Arduino with out having to use a AC plug to USB adapter
to get power to the iPod Touch. I assembled an AC adapter
the other day for the Arduino, and the specs are as follows:INPUT: 120VAC 60Hz 21.6W
OUTPUT: 12VDC 850mA
Now, I understand from watching this video
that the iPod Touch 2G, iPhone 3G(S) require precise voltages in order to charge from different power sources. If a late iDevice (one of three described above) is plugged into a USB port of a computer, the computer can only provide 500mA (USB spec), and the voltages traveling across the data pins (D+ and D-) of the USB port/cable have to be 2.0VDC, but if the device is charging from the MB352LL
using 1A, then the voltages need to be 2.8VDC on D- and 2.0VDC on D+. I am totally content with providing the iPod Touch 500mA using the Arduino, but I understand that the digital out pins can only provide 40mA of current for each pin. So is there some way I can make sure I can provide a steady 500mA to the iPod Touch using a pass through from the Arduino AC power source of some sort?