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Use composite/CVBS AV IN as front view cam and dash cam

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By jorisvervuurt, Member on 3rd June 2018, 06:04 PM
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I have a PX5 head unit running Android 8.0 Oreo. I’ve already connected a rear view camera that works great, but I’d also like to connect a front view camera. I’ll be connecting the camera to the composite/CVBS AV IN video input.

I don’t expect any problem using it simply as a front view camera by launching the AV IN app to view the video signal, but I was wondering if it is possible to use the same video signal for the DVR dash cam app (I know the quality won’t be all that great, but still)?

Also, the AV cable harness of my head unit includes a red ‘CAM POW’ wire. I haven’t measured yet, but perhaps somebody knows if it gets 12V when the radio is on? Otherwise I’ll have to look for a different 12V source. I’ve already enabled the ‘Front cam’ option in the Factory settings and I’ve set the ‘DVR’ option to ‘USB+CVBS’.
 
 
4th June 2018, 09:49 AM |#2  
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4th June 2018, 12:05 PM |#3  
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The cam pow wire will output 12v when the F-cam app is open (or when reverse gear is triggered via the reverse wire).

I don’t know of a way to use that video for the DVR app, and moreover the front/rear cameras typically have a voltage converter from 12v to whatever lower voltage the camera itself uses. This is integrated either into the camera or on the wire somewhere and it warms up very quickly. The camera isn’t meant to be on all the time as a result because it overheats and can stop working.

The DVR app is made to receive a signal from a certain type of USB camera only afaik. You can find them on AliExpress too.. then again I gotta check my settings, because I’ve never messed around with it.
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4th June 2018, 03:17 PM |#4  
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Quote:
Originally Posted by vassandrei

The cam pow wire will output 12v when the F-cam app is open (or when reverse gear is triggered via the reverse wire).

I don’t know of a way to use that video for the DVR app, and moreover the front/rear cameras typically have a voltage converter from 12v to whatever lower voltage the camera itself uses. This is integrated either into the camera or on the wire somewhere and it warms up very quickly. The camera isn’t meant to be on all the time as a result because it overheats and can stop working.

The DVR app is made to receive a signal from a certain type of USB camera only afaik. You can find them on AliExpress too.. then again I gotta check my settings, because I’ve never messed around with it.

I see, thanks for the detailed reply!
I’ll forget about using this camera as a dash cam.

Do you know if the CAM POW wire also outputs 12V when the AV IN app is open? Or is it just when the F-Cam app is open (and set to the front cam)?
4th June 2018, 07:58 PM |#5  
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Quote:
Originally Posted by jorisvervuurt

I see, thanks for the detailed reply!
I’ll forget about using this camera as a dash cam.

Do you know if the CAM POW wire also outputs 12V when the AV IN app is open? Or is it just when the F-Cam app is open (and set to the front cam)?

That's a good question.. I haven't tested. I'll try tomorrow and tell you the result. I'm going to lean towards no though, because otherwise anytime that AV-in would be open my rear/front camera and parking system would turn on, which would be inconvenient if watching some AUX video in source (like a console).
4th June 2018, 08:06 PM |#6  
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Quote:
Originally Posted by vassandrei

That's a good question.. I haven't tested. I'll try tomorrow and tell you the result. I'm going to lean towards no though, because otherwise anytime that AV-in would be open my rear/front camera and parking system would turn on, which would be inconvenient if watching some AUX video in source (like a console).

Awesome, thanks!

Another question...
My head unit only has two (yellow) RCA video inputs.
One is labeled 'CAM VIN', to which my reverse camera is connected.
The other input is labeled 'AUX VIN' (also a yellow RCA).
Is my assumption that F-Cam uses the 'AUX VIN' signal correct (so, the same signal that is shown in the AV IN app)?
5th June 2018, 10:19 AM |#7  
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Quote:
Originally Posted by jorisvervuurt

Awesome, thanks!

Another question...
My head unit only has two (yellow) RCA video inputs.
One is labeled 'CAM VIN', to which my reverse camera is connected.
The other input is labeled 'AUX VIN' (also a yellow RCA).
Is my assumption that F-Cam uses the 'AUX VIN' signal correct (so, the same signal that is shown in the AV IN app)?


Alright so I tested and the AVIN app has no effect on the CAM-POW pin, because my parking sensors and rear/front cameras definitely don’t turn on when I open the avin app.

Cam-VIN is your reverse camera in most likely. It will show when you give the reverse pin 12v and thereby activate the reverse camera app (or open the f-cam app and switch to rear view mode via the button on the screen).

Aux vin is what the AVIN app shows, and is not tied to any power pin as far as I know.

F-cam in is separate from those two and the connector isn’t always present on all units. You might have the f-cam in pin on a second AV connector that doesn’t have any plugs included for it (for instance on my unit f-cam in is on a small 8 pin connector next to my main av connector which I had to make my own cables for)

Check the front parking camera mod thread on here, I posted pictures of what my Witson unit looks like.
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5th June 2018, 03:25 PM |#8  
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Quote:
Originally Posted by vassandrei

Alright so I tested and the AVIN app has no effect on the CAM-POW pin, because my parking sensors and rear/front cameras definitely don’t turn on when I open the avin app.

Cam-VIN is your reverse camera in most likely. It will show when you give the reverse pin 12v and thereby activate the reverse camera app (or open the f-cam app and switch to rear view mode via the button on the screen).

Aux vin is what the AVIN app shows, and is not tied to any power pin as far as I know.

F-cam in is separate from those two and the connector isn’t always present on all units. You might have the f-cam in pin on a second AV connector that doesn’t have any plugs included for it (for instance on my unit f-cam in is on a small 8 pin connector next to my main av connector which I had to make my own cables for)

Check the front parking camera mod thread on here, I posted pictures of what my Witson unit looks like.

Thank you so much!
I've checked the other thread and I may be in luck with the 8 pin connector.
Mine's also a Witson unit: http://www.witson.com/en/displayprod...roID=102131570

I don't have a photo of the actual unit in my car, but according to Witson's product photo it does have the 8-pin connector:


I currently have my reverse camera connected to CAM VIN (video signal, yellow RCA) and the +12V to the brown REVERSE wire on the main ISO harness.
That brown REVERSE wire gets +12V when I manually change gear to the reverse gear (otherwise it's at 0V, I've measured it), but clicking the reverse camera button in F-Cam doesn't get me +12V on that wire.

If I understand correctly, you have both your front view camera and your reverse camera connected to the red CAM POW wire on the AV-harness?
Does the radio output +12V on the red CAM POW wire when you manually change gear to the reverse gear AND when clicking the reverse camera button in F-Cam?
If so, I'll have to change the wiring.

As for the 8-pin connector: what is it called and where can I order the correct harness?

Thanks again for all the useful info!!!
5th June 2018, 07:56 PM |#9  
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Quote:
Originally Posted by jorisvervuurt

Thank you so much!
I've checked the other thread and I may be in luck with the 8 pin connector.
Mine's also a Witson unit: http://www.witson.com/en/displayprod...roID=102131570

I don't have a photo of the actual unit in my car, but according to Witson's product photo it does have the 8-pin connector:



I currently have my reverse camera connected to CAM VIN (video signal, yellow RCA) and the +12V to the brown REVERSE wire on the main ISO harness.
That brown REVERSE wire gets +12V when I manually change gear to the reverse gear (otherwise it's at 0V, I've measured it), but clicking the reverse camera button in F-Cam doesn't get me +12V on that wire.

If I understand correctly, you have both your front view camera and your reverse camera connected to the red CAM POW wire on the AV-harness?
Does the radio output +12V on the red CAM POW wire when you manually change gear to the reverse gear AND when clicking the reverse camera button in F-Cam?
If so, I'll have to change the wiring.

As for the 8-pin connector: what is it called and where can I order the correct harness?

Thanks again for all the useful info!!!

The reverse wire is meant to receive 12v+ into the head unit as a signal of you having changed gears. It's typically hooked up to your reverse light (as it turns on when you switch into reverse).

and YES! The CAM POW wire outputs 12v BOTH when in reverse gear (triggered by the reverse signal wire receiving 12v) AND when opening the f-CAM app!! It's actually super cool because not only is it an automatic parking assistance system (for both front and rear) but you can totally check either camera at ANY time, even during driving, or being stuck in traffic. It's quite fun

Yes, I currently have both my front and rear camera powered by the CAM POW wire. I did use a relay though, so as not to overload the one pin (because I have a video-based parking sensor system installed on both the front and rear as well).

The 8 pin connector -- I have no idea what it's called. I just dug around through my old head unit connectors from my other car and found one that was the same size but wider. I cut it so that it was 4 pins (instead of something like 16). So, if someone else knows what those types of connectors are called, that would be helpful.
5th June 2018, 09:05 PM |#10  
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Quote:
Originally Posted by vassandrei

The reverse wire is meant to receive 12v+ into the head unit as a signal of you having changed gears. It's typically hooked up to your reverse light (as it turns on when you switch into reverse).

My head unit has two brown REVERSE wires; one on the main ISO harness and one on the AV harness. The one on the AV harness never outputs +12V, as it is the trigger wire. The REVERSE wire on the main ISO harness however, does output +12V when I manually select reverse gear. This is done through the CANbus system. My reverse camera is not connected to the reverse light wiring.

Quote:
Originally Posted by vassandrei

and YES! The CAM POW wire outputs 12v BOTH when in reverse gear (triggered by the reverse signal wire receiving 12v) AND when opening the f-CAM app!! It's actually super cool because not only is it an automatic parking assistance system (for both front and rear) but you can totally check either camera at ANY time, even during driving, or being stuck in traffic. It's quite fun

That sounds great! I’ll be measuring some of these wires soon, as I’m probably going to change the wiring. It’ll be particulary useful to read license plates of cars that are ‘bumperklevers’ as we call them in Dutch.

Quote:
Originally Posted by vassandrei

Yes, I currently have both my front and rear camera powered by the CAM POW wire. I did use a relay though, so as not to overload the one pin (because I have a video-based parking sensor system installed on both the front and rear as well).

Hmm, okay. Will that also be necessary when connecting two simple cameras, of which one has four white LEDs? I guess they won’t use that much power.

Quote:
Originally Posted by vassandrei

The 8 pin connector -- I have no idea what it's called. I just dug around through my old head unit connectors from my other car and found one that was the same size but wider. I cut it so that it was 4 pins (instead of something like 16). So, if someone else knows what those types of connectors are called, that would be helpful.

Aha, okay. I’ll ask the seller of my radio.
6th June 2018, 07:41 PM |#11  
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@vassandrei I have just (without taking the radio out of the dashboard) measured the red CAM POW wire on the AV-harness.

Good news! Normally, the wire reads 0V. When I open the F-Cam app - no matter if the front or back camera is selected - it reads +12V. This is also the case when the reverse gear is selected, even when the F-Cam app is not opened.

Note that all of the above is working without having the reverse trigger wire connected to the reverse light positive; all through the CANbus system.

I’m going to change how my reverse camera is connected, as it right now only gets power when I select the reverse gear.
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