Detect video and communications

[pcleats]

Hello all,

Is there an easy way to get the zx-24 to detect a video signal? All I need it to do is be able to detect a video signal, and if one is present light an LED.

Also I would like to connect 2 zx-24's together, what is the best way to do this. I am not very familar with serial communications. I will be connecting 250 ft lengths of wire up a max length of 1000ft.

Any help would be appericated.

Patrick

[stevech]

video detector - - video fed to anode of a diode to a resistor divider then into an I/O pin of the ZX. I'd think that sofware could detect the horizontal and vertical synch pulses that go below zero volts and thus back-bias the diode.

serial - you'll need to connect the serial data lines on the ZX to an RS232 line driver. These can be had for $10 as a PC board, or you can fabricate one. With RS232, at moderate baud rates, and with the proper wire, you can usually get 100-200 ft. But beware this one: if the two ends of the link are powered by different AC mains sources, you may get a ground loop between the two causing high error rates. You can overcome this by using a differential line driver like RS422 instead of RS232. Or go wireless, say, with a pair of $20 Maxstream 802.15.4 XBee radios or the $40 version with higher power.

Someone else here may have other/better ideas.