xenac and switching inputs

Zeinin · 12-30-2002, 11:43 AM

how does one go about switcing inputs on the xenac? in a perfect wolrd there would be a lead that would switch the input when a voltage is applied to it, but i doubt that that is the case. i want to hook up a revese camera that would automaticly take control of the display when the car is in reverse.

thenominous · 12-30-2002, 05:35 PM

Do you own one currently?
If so, how do you switch between the inputs at the moment (I dont know, I dont have one).
Chance's are if you want to do this, you will have to hack the switch that change's the input. Some thin wire inside the case, soldered to the switch contacts, terminating to a socket on the back of it.

Dave

alear · 12-30-2002, 08:21 PM

I agree with Dave. The switch probably closes a circuit the gets grounded or powered to tell the screen to switch inputs. You can create a parallel circuit to the switch that closes the connection. If there are more than two inputs then your circuit will need to keep track of which input is currently selected (by monitoring its own changes and the changes by the user pressing the switch). It could then switch to the camera and back depending on your cameras signal.

Jay · 12-30-2002, 09:35 PM

I have one. The way you switch is there is a “s” button on the front panel and you tap it to cycle through the inputs. When you turn the unit on it pulls up the last input that you were on. Not sure which one you have but I have the one with 3 composite inputs and 1 video feed (VGA). I also would like to so the same thing however its not on the immediate agenda. What I was going to do is get a USB camera and when I hit reverse, send a single to a VB app that would full screen the software that would display the output of the camera. I’m thinking…you’ll have to build a circuit….the input would be a switch connected to the shifter (something that will sense reverse) and output could be tied to a relay that would be connected to the “s” button (You’ll have to jump the leads on the board. When you hit reverse, have a 555 timer circuit would “tap” (meaning close the circuit on the button) the “s” once and when input goes low (take the car out of reverse), “tap” the button three times to bring it back to the VGA input. Clunky but it would work.

I still recommend going with a USB video feed.

alear · 12-30-2002, 10:17 PM

The software app is one way to go, but you are somewhat limited to usb cams and you still need to input the signal to the computer.

I still like the circuit to flip video inputs. I agree with you on the circuit but get rid of the 555. Just use an 8-pin atmel tiny. Same size as the 555 but without all the external components and then you have precise control on switching and you can monitor which input is currently selected so you can go back to it. Can't always assume vga is selected.

Zeinin, I'm going to be doing this to mine in about a month. If you want to wait, I'll put up a how-to and post the microcontroller code.

Jay · 12-30-2002, 10:24 PM

Alear,
I haven't been in the elec. world for a while so thats why I suggested the 555 timer, sorry about that. From what you are stating, its pretty easy. Also because there are three inputs, one could camera up each side mirror also. Please keep us updated on your progress, I'm also interested in it. Thanks.

alear · 12-30-2002, 11:39 PM

Quote:

Originally posted by Jay
Alear,
I haven't been in the elec. world for a while so thats why I suggested the 555 timer, sorry about that. From what you are stating, its pretty easy. Also because there are three inputs, one could camera up each side mirror also. Please keep us updated on your progress, I'm also interested in it. Thanks.

Sounds good, I was just suggesting a better way. I'll keep you notified by this thread. Like I said, it will probably be a month before I do it. I'm waiting for Armen to get those xenarc's in stock so I can get one. I know exactly how I'll do it and the software is relatively simple. I will probably have to program the microcontroller and send them out to anyone that wants one (don't worry they are only a few dollars). 1 or 2 wires will have to be soldered inside the display case but it shouldn't be too bad.

Zeinin · 12-31-2002, 02:52 AM

okay, so its a tap system... thats a bit easier than a two button system.

hmm, im going to have to do a bit more modification than i wanted to. basicly im going to take the reverse light and feed off of that to a parrlle port input. the pport would interface with a vb app (c++ if i feel like i need to) and tap the button one time. when the reverser lead goes low, it would tap the button 2 more times. woo

Dtstyle · 01-01-2003, 08:27 PM

go to radio shack and find an electronic video switcher. You wouldn't even have to use the computer. I would use a DTSP switch with the off in the middle. Have the top be on, middle be off, and bottom be auto switch. Thatway you have complete control.

edit: like this switch: http://www.radioshack.com/product.as...5Fid=15%2D1587

thenominous · 01-02-2003, 12:07 PM

That's a handy device for switching composite, but the xenarc needs to switch between the VGA input and a composite one.
It is also a manual one, where as the idea was for a one controlled automatically. For switching composite, you could just get away with a relay.

Dave

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