Can someone explain in detail what and how the Accessory Cable (3 wire) works?

Iggy

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OK all you electronic techies out there I have a few questions to ask about the A119 V3 Accessory cable.


I have a question regarding the accessory mode cable that VIOFO sells.
I’m electronically savvy and was wondering about the Yellow and Red Wire setup.
I know that the Red is a constant + 12 VDC and the Yellow is +12 volts DC when car is running.

My question is if I didn’t care about my battery and wanted to run the camera 24/7 How does it know it’s in parking mode?

Question #1
Does the camera sense the loss of Accessory Voltage but sees the 2nd 12 volt + is still hot straight from the battery?

Or

Question #2
Does that little voltage regulator/cutoff box in the cable does something special?

Or

Question #3
Does that Accessory cable actually have two 12 volt + circuit in the micro USB plug in the GPS/Camera?

I’m just trying to figure out if that accessory cable even with the low voltage cutoff is nothing more than a voltage regulator cutout or is it more.
 
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Iggy

Iggy

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I guess no Techies out there.
Oh well.
 

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It’s very late here but in brief there is two ic’s on a small cct board.
Both chips are 8 pin dips.
While the chips appear to look the same one has no printing on it and the other I can’t find what it is.
My tomorrow I’ll post a picture and the chips code.
From another forum post apparently the yellow wire connects to one of the data lines but I haven’t checked this.
Identifying the chip would help to work our what’s going on.
Hope that answers some of your question.
 
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Iggy

Iggy

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Thanks LateralNW for your help. Sounds as if you know about free electrons.

One part obviously is a method to step down the voltage from 12 + to 5+.
One chip must be monitor the input voltage accordingly to the switch location/ low voltage setting before cutout voltage is met.

The real question I want to know is does the this box actually have two seperate 5+ circuits going to the camera/gps or is it only one +.
You see I want to know how the A119 V3 knows it went from driving mode to parking mode via power from the cable.
That is my big question.
 

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The USB connector on the A119 V3 has ground, +5V power, and a parking mode signal which is something less than 5 volts and does not carry power.
 
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The USB connector on the A119 V3 has ground, +5V power, and a parking mode signal which is something less than 5 volts and does not carry power.

Thanks Nigel that tell me a lot more what I was wondering how the camera knew it was in parking mode. If that is true then it as you say has 2 seperate + power sources from the box to the camera.
And with that you must have that ACC Cable to make it work in parking mode.
We will see what others may bring to the table.
 

Nigel

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Thanks Nigel that tell me a lot more what I was wondering how the camera knew it was in parking mode. If that is true then it as you say has 2 seperate + power sources from the box to the camera.
And with that you must have that ACC Cable to make it work in parking mode.
We will see what others may bring to the table.
You can connect the ACC input to the same place as the power input if you wish - both to the same fuse tap.
With the A129 you must connect the ACC input before it will wake up, not sure about the A119, never tested it.
 

IAmATeaf

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I thought the 3 wire cable sent some sort of pulse on the data pins which the cam interprets? This together with the GPS sensor and it logically works out that the car is off and not moving? But I could be talking a crock [emoji3]
 
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I thought the 3 wire cable sent some sort of pulse on the data pins which the cam interprets? This together with the GPS sensor and it logically works out that the car is off and not moving? But I could be talking a crock [emoji3]

That's what I think until someone comes and really tells us the truth. WE CAN HANDLE THE TRUTH!
or
The a single free electron in the dash cam watches out the lens and knows when you park and tells his chip friend "we are parked" and magic happens. Hummm possible?
 

CaptureYourAction

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The yellow wire is simply a trigger wire. It simply tells the camera when the car is running and when it's not. Based on if there is voltage at the yellow wire or not, the camera knows when to enter parking mode and when to exit parking mode.

Both the red and yellow wire need to be connected, even if you don't want to use parking mode.
 

speedlever

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Pardon my ignorance, but does the yellow wire simply need to be connected to the same power source as the red wire?
 

CaptureYourAction

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Pardon my ignorance, but does the yellow wire simply need to be connected to the same power source as the red wire?
If you don't want to use parking mode, then yes, you can wire it that way. However, the kit won't trigger parking mode unless the yellow wire is on it's own accessory fuse.
 
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Iggy

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I just found on this forum the exact question I'm asking.
It was back in September 2019 and no one was able to finalize or verify exactly how the A119 V3 senses when the engine is off and goes to parking more.
It seems it's a tough question only VIOFO can answer.
 

lacibaci

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The yellow wire is simply a trigger wire. It simply tells the camera when the car is running and when it's not. Based on if there is voltage at the yellow wire or not, the camera knows when to enter parking mode and when to exit parking mode.

Both the red and yellow wire need to be connected, even if you don't want to use parking mode.
This is the correct answer for most cameras. Of course a camera can do additional logic based on accelerometer and GPS to determine if it is moving.
 
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Iggy

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I came across this diagram from the other thread someone showing the main power to the USB plug but also the additional signal + which may be part how the A119V3 knows its in parking mode.
7f9686f773897c9c6946880cb377ace2.gif
The Black is Ground
The GREEN and the RED I have to figure out which is ACCessory Mode and which is Main Continues Battery Power on ALL the time.

Now for some testing.
 

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The GREEN and the RED I have to figure out which is ACCessory Mode and which is Main Continues Battery Power on ALL the time.
From memory, I believe the voltage on the ID pin (4) reflects the on/off state of the ACC input to the 3-wire hardwire kit.

Red is power (+5 volts), black is ground (0 volts).
 

IAmATeaf

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From memory, I believe the voltage on the ID pin (4) reflects the on/off state of the ACC input to the 3-wire hardwire kit.

Red is power (+5 volts), black is ground (0 volts).

Now that makes sense as pin 4 is specifically designed to provide detection.
 

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If you don't want to use parking mode, then yes, you can wire it that way. However, the kit won't trigger parking mode unless the yellow wire is on it's own accessory fuse.
Thank you. There are no instructions that come with the 3 wire kit. How is one supposed to know that?
 
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Iggy

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Thank you. There are no instructions that come with the 3 wire kit. How is one supposed to know that?

This information we are talking about is more for us inquisitive minded people in knowing how things work.
The 3 wires from the kit are marked RED always hot, YELLOW is for ACC only hot when ignition is ON and BLACK is ground.
 
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