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Constructing an automatic RCA video camera feed splitter

 
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Airdog77



Joined: 24 Nov 2013
Posts: 80
Location: Northern Virginia

PostPosted: Wed Oct 11, 2017 8:05 am    Post subject: Constructing an automatic RCA video camera feed splitter Reply with quote

Hi Bob, et al.

I recently purchased a GRT EFIS for the Long-EZ that I'm building. The GRT EFIS has an option to connect up a single video feed to it via USB (in this case, my 4-port USB hub). I've tested out some mini-video cameras I picked up off of Amazon that are about the size of a dime, and the picture quality is great for what I want to use them for.

As I'm sure many of you know, most canard aircraft have fuel site gages in the back seat area. Look inside these birds parked on the ramp and invariable you'll find a mirror, which is what canard pilots often use to check out their fuel site gages in the back. I figured with such diminutive sizes on these cameras, why not hook one up focused on each site gage, and while I'm at it point a 3rd camera looking aft at the engine from atop the pilot head rest. A 4th camera on the bottom CL looking aft would be round out my initial camera installation.

My issue is that I would like to have a timed cycle display of each of these camera views in a little window on my EFIS (GRT has taken care of the EFIS display part), say 3-5 seconds per camera. However, every RCA jack 4-into-1 video channel selector I have found --while cheap-- are bulky plastic housing a large mechanical switch to select the video channel.... mainly used by video gamers. I talked with GRT and any machinations going on with the video feed is fine, as long as only one physical RCA video jack is presented to their USB video input device.

I would like to construct a 4x (or more) channel IN and 1x RCA jack channel out device that is small, and automatically cycles through each camera view, again for 3-5 seconds. Adjustable viewing times would be good, and maybe a manual pause or cycle button would be good as well.

Does anybody know of a device like this that exists? Would the circuitry for something like this be too complicated? Finally, is there any detriment to swapping out the thicker RCA cabling with 24 AWG shielded wire?

Thanks!
Wade


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Airdog
Wade Parton
Building Long-EZ N916WP
www.longezpush.com
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alec(at)alecmyers.com
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PostPosted: Tue Oct 17, 2017 3:44 am    Post subject: Constructing an automatic RCA video camera feed splitter Reply with quote

Let’s use a 16F630.

It has enough pins to:
-use two buttons, which can be independently detected, and therefore pressed together
-use solder pads/jumpers for speed rather than a pot, therefore cheaper, reduction in component count, and less board space. If you really want to “twiddle” something use a coded rotary switch (which is roughly the same price as a pot) for development and short the pads with solder blobs instead later
-have more than 4 cameras
Also strongly strongly recommend a SOIC package (cheapest) which is smaller and still hand solderable. Fewer holes makes for an easier pcb too. It’s 2017!

Happily the 16f630 is exactly the same price as the 12f683.

On Oct 17, 2017, at 00:45, Eric Page <edpav8r(at)yahoo.com> wrote:



I'm convinced that using a PIC is the way to go. I'd also like to give the CD4066 a try as the switch.

Once we hear from Wade that his EFIS and video adapter handle the camera feed switching OK, I'll edit the schematic and work on a board layout. Then Alec/Paul can write some code. Here's what I'd like to accomplish with the software:
1. At power-up, wait a bit for the regulator to settle, then read voltage on AN3/Pin3 and correlate to scan rate (0-5V = 2-10 sec per camera).
2. Start scanning at camera 1, then 2, 3, 4, 1, etc.
3. Monitor the switch(es) and respond as follows:
- Short press R or L: During scan mode, stop scan. During hold mode, advance one camera forward (R) or back (L).
- Long press R or L: During scan mode, reverse scan direction if switch is moved opposite to current scan direction. During hold mode, begin scan forward (R) or back (L).
Installation with an (ON)-ON-(ON) toggle switch would work as above. Installation with a single pushbutton would have the switch connected as the RIGHT position of the toggle, and would function as follows:
- Short press: In scan mode, stop scan. In hold mode, increment by one camera.
- Long press: In scan mode, no change. In hold mode, begin scan from current camera.
I've done a quick demo layout with the PIC and CD4066, so I could figure out the best GPIO assignments. See "Demo_Layout.jpg" below.

"Mode_Sw_AN2.jpg" below shows my best guess at how to attach the (ON)-ON-(ON) toggle switch to AN2/Pin5. Please let me know if there's a better way to do it.

Eric


Read this topic online here:

http://forums.matronics.com/viewtopic.php?p=473636#473636


Attachments:

http://forums.matronics.com//files/demo_layout_145.jpg
http://forums.matronics.com//files/mode_sw_an2_270.jpg


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PostPosted: Tue Oct 17, 2017 3:46 am    Post subject: Constructing an automatic RCA video camera feed splitter Reply with quote

And whichever PIC we use, make sure to provide access to the ICSP pins!

On Oct 17, 2017, at 00:45, Eric Page <edpav8r(at)yahoo.com> wrote:



I'm convinced that using a PIC is the way to go. I'd also like to give the CD4066 a try as the switch.

Once we hear from Wade that his EFIS and video adapter handle the camera feed switching OK, I'll edit the schematic and work on a board layout. Then Alec/Paul can write some code. Here's what I'd like to accomplish with the software:
1. At power-up, wait a bit for the regulator to settle, then read voltage on AN3/Pin3 and correlate to scan rate (0-5V = 2-10 sec per camera).
2. Start scanning at camera 1, then 2, 3, 4, 1, etc.
3. Monitor the switch(es) and respond as follows:
- Short press R or L: During scan mode, stop scan. During hold mode, advance one camera forward (R) or back (L).
- Long press R or L: During scan mode, reverse scan direction if switch is moved opposite to current scan direction. During hold mode, begin scan forward (R) or back (L).
Installation with an (ON)-ON-(ON) toggle switch would work as above. Installation with a single pushbutton would have the switch connected as the RIGHT position of the toggle, and would function as follows:
- Short press: In scan mode, stop scan. In hold mode, increment by one camera.
- Long press: In scan mode, no change. In hold mode, begin scan from current camera.
I've done a quick demo layout with the PIC and CD4066, so I could figure out the best GPIO assignments. See "Demo_Layout.jpg" below.

"Mode_Sw_AN2.jpg" below shows my best guess at how to attach the (ON)-ON-(ON) toggle switch to AN2/Pin5. Please let me know if there's a better way to do it.

Eric


Read this topic online here:

http://forums.matronics.com/viewtopic.php?p=473636#473636


Attachments:

http://forums.matronics.com//files/demo_layout_145.jpg
http://forums.matronics.com//files/mode_sw_an2_270.jpg


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Eric Page



Joined: 15 Feb 2017
Posts: 241

PostPosted: Tue Oct 17, 2017 9:02 pm    Post subject: Re: Constructing an automatic RCA video camera feed splitter Reply with quote

alec(at)alecmyers.com wrote:
Let’s use a 16F630.

It has enough pins to:
-use two buttons, which can be independently detected, and therefore pressed together
-use solder pads/jumpers for speed rather than a pot, therefore cheaper, reduction in component count, and less board space. If you really want to “twiddle” something use a coded rotary switch (which is roughly the same price as a pot) for development and short the pads with solder blobs instead later
-have more than 4 cameras


OK, PIC16F630 it is. That and another CD4066 to support eight cameras has exceeded the space in any D-Sub backshell I could find, so I'll just design for a flanged plastic box:



After another quick-and-dirty layout test, the PIC pins shake out like this:

    01: Vdd
    02: Camera 3 Select
    03: Camera 2 Select
    04: Panel Switch (Left) / Vpp
    05: Rate Program Switch
    06: Camera 8 Select
    07: Camera 5 Select
    08: Camera 6 Select
    09: Camera 7 Select
    10: Cams Program Switch
    11: Panel Switch (Right)
    12: Camera 1 Select / ICSP Clock
    13: Camera 4 Select / ICSP Data
    14: Vss


I'd like to hide the programming functions behind DIP switches so the interface for normal operation stays stone simple. Since there's no display or indicator LEDs, I want no possibility of accidentally entering a programming mode. I see the two programming DIP switches working like this:

    - To set number of cameras, the installer closes the Cams Program Switch, then powers up the unit. It displays Camera 1 in hold mode. The installer uses the Panel Switch (Right) to increment through each camera until the last one is displayed, then opens the Cams Program Switch to tell the PIC to save the number of cameras to non-volatile memory. The installer then cycles power and it reads the saved number of cameras from memory and begins normal operation. [The PIC could be programmed with a zero in this memory cell, which would make it enter this mode automatically at power-up, until a non-zero number is saved.]

    - To set scan rate, the installer closes the Rate Program Switch, then powers up the unit. It goes into scan mode and Panel Switches (Left) and (Right) increment and decrement the scan delay time (in 1 sec steps, between 2 and 10 sec). When the desired time is achieved, the installer opens the Rate Program Switch, which tells the PIC to save the rate to non-volatile memory. The installer then cycles power and it reads the saved scan rate from memory and begins normal operation. [Again, a default value could be programmed. Say, 5 sec.]


Quote:
Also strongly strongly recommend a SOIC package (cheapest) which is smaller and still hand solderable. Fewer holes makes for an easier pcb too. It’s 2017!


I would use all SMD parts in a heartbeat if I were designing this for myself or a limited audience of people with the right soldering equipment and skill. I agree SOIC parts are easy to solder, but you and I have used a lot of them. For an airplane builder whose soldering experience might be limited to joining wires together, and who doesn't have a magnifier lamp or microscope, a SOIC part is going to be a source of massive frustration. To say nothing of the 0603 or 0805 passives that go along with it. Besides, the price premium for DIP-vs-SOIC is $0.14. We ain't going into high-rate production here! Besides, DIP packages give me lots of room to run ground pours between all of the video signal traces.

Quote:
And whichever PIC we use, make sure to provide access to the ICSP pins!

Noted.

Eric


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