Thanks for all the ideas - thanks especially for the circuits, Jinx! I'm very much an amateur at all this, so I'm going to have to take time to absorb and research what you all have given me. I'm not sure what the Manchester technique is, but I had counted on some sort of checksum and an LED on the board to indicate success/failure. Low baud rate is fine - I only need a few bytes of data. In fact, I may be able to combine 2 or 3 values into one byte. If it takes 2 or 3 seconds, it's no big deal. Since my programming ability is orders of magnitude greater than my electronics knowledge, I may try the software route to filter out noise. However, the 60 Hz noise might be something easier done on the hardware end. Again, more research needed here. I'll pursue this over the next week or so and report back. If there are any more suggestions... I'll be watching and saving them. Thanks again, Jeff Quoting Bob Ammerman : > 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 > -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email listserv@mitvma.mit.edu with SET PICList DIGEST in the body