I need to transfer data from my Windows Phone 7 to mC. The problem is that WP7 doesn't have any type of usb client control. So I was thinking, I could connect photodiode to mC, change in voltage will be used to represent data. I have already coded 32 characters using two voltage states, that should be enough. Light will be emited from WP7 screen, just flashing black/white when in sending mode. I would isolate external by building a stethoscope-like fraim for diode. My question is what model of photodiode should I use? Changes in screen light will be every 20 ms. Do I need some kind of amp for voltage from diode ?
I'd start with any IR phototransistor you can get your hands on; basically whatever is available at the local electronics store. A round/5mm instead of a rectangular one would probably be the best. If you can isolate it well and you're holding the phone closely you shouldn't have a problem.
If you can get your flash rate up to around 38khz then you could use an IR receiver and you'd have the amp built in.
Thank you for replying. What kind of amp circuit should I build? Would something like 741 DIP OPAMP, 3-18V, 1MHz, GENERAL PURPOSE, DIP8 be useful?