Do you need to switch the charging on and off? If not you could run the Vcc to the device but that's putting a lot of power through the Arduino regulator (3.5 watts - much more than it can handle).So you will need a separate regulator with moderate/large heat sink to pass 5V 0.5A to the device. The control voltages may be generated with voltage divider to the D+ and D- pins - assuming they don't draw significant current.
woah woah, the D+ and D- are for signalling use only. you wont get any power off those lines. it can recharge and stay powered because... well, thats how they designed their circuit. power the main board first, then use extra current to pump into the battery.
I am in middle on trying to assemble aipad case 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 iPad2 case to get power to the iPod Touch. Iipad 2 casethe other day for the Arduino, and the specs are as follows:[font=Courier New]INPUT: 120VAC 60Hz 21.6WOUTPUT: 12VDC 850mA[/font]Now, I understand from watching 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 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?
Yeah I understand from USB spec that voltage isn't supposed to be transmitted over D+ and D- but Apple didn't conform to USB spec with the newer devices :-/ That's how I understand it at the moment. If you watch the video stated above in the post the lady in the video does a good job explaining iDevice charging
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