You are going to have to be able to live with a very low baud rate (10 baud?), but this is certainly very doable. I would use a self-clocking technique like Manchester. You will need some reasonable checksum/crc protection. Also, you'll want the device to be able to indicate success/failure (blinking light). On failure of course you just do a retry. You probably want an RC filter (or software filtering) on the signal from the photosensor to deal with issues like phosphor persistence and LCD refreshing. Bob Ammerman RAm Systems ----- Original Message ----- From: "Alex Harford" To: Sent: Tuesday, March 30, 2004 5:40 PM Subject: Re: [EE:] Phototransistor as Serial Input? > On Tue, Mar 30, 2004 at 04:49:13PM -0500, Jeff Swayze wrote: > > Has anyone done anything like this before? I think it would be relatively straight forward, but I'm not sure how to filter and > > massage the input from the phototransistor. Any help would be appreciated. > > IIRC there was a Timex watch/pda that allowed you to set alarms on the watch > using a PC program. > > I'd image the difficulty would be in getting the timing correct if you are > using a win32 platform. Windows timers aren't very accurate, and I'm not sure > if you can access the accurate timers in the video card. > > This is a really cool idea though, keep us posted! It would be nice to be able to emulate a serial port through the monitor, using the schematic that Jinx > posted on the PIC side. > > -- > Alex Harford > http://www.alexharford.com > alex-spam@alexharford.com Tel: (604) 738-5674 > > -- > http://www.piclist.com#nomail Going offline? Don't AutoReply us! > email listserv@mitvma.mit.edu with SET PICList DIGEST in the body > -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email listserv@mitvma.mit.edu with SET PICList DIGEST in the body