Hello.
I new user.
I need make measurement of car voltage with Android OS on VIM3.
How do it?
@MaxPain, You cannot do this directly, you will need some sort of voltage sensor connected to the VIM3, probably by I2C or maybe some other GPIO, I am not sure if a ADC is present on the VIM3 GPIO,
also you will need to the suitable library or module associated with the sensor used,
decide on a suitable sensor and try to associate it with its correct drivers, the community will followup on this topic if you were able to get those two steps successfully, here is the GPIO layout of the VIM3 for reference,
By the way welcome to the community, 
Reference to more board details here :Khadas VIM3 docs
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Hmm . I think Pin10, and Pin12 - for this.
yes sorry I did not see that, but it cannot be connected directly, i think car batteries are in the range of 12v
connecting it would obviously result in the magic white smoke 
If you are good at basic engineering you could try this to have a simple sensor, 
Where,
Adjust Vout to be in the right voltage range
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Hello, For me personally, I would want isolation(optical, transformer, etc) between car and VIM3 for measuring car system voltage. GPIO offers ADC on pins 10 and 12. Devices(search term: voltage detection module) made for Arduino or Pi using ADC(Analog-To-Digital-Converter) are available, look like a very simple circuit. But those seem to lack isolation. Also, how you would make it useful for Android is not known to me.
Another option would be to use an OBDII Bluetooth device to send an android app voltage and most other relative automotive data. User @tschultz made a dashboard display for his truck. Maybe you can get some ideas reviewing that thread.
Also user @davemf has done some automotive projects, clicking his name will take you to a page with his posts and projects.
Hope it helps.
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Well said, @RDFTKV,
@MaxPain do search around the forum for more information about it, definitely keep the sensitive electronics in isolation from high voltage stuff like RDFTKV said, maybe you could use isolators to prevent such mishaps from killing your precious electronics
Do refer @tschultz project, you could learn more from it, good day
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I also thought to add this on,
Most cheap sensor use the above resistor bridge to measure voltage,
One way I could suggest is measuring the voltage, temperature, etc (If that is also going to be measured)
with a ardunio like device and pass the info along to the board, so that it is isolated but the data is measured close to the source.
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Yes, that’s all right. I need to read the fuel level. I also want to make an e-cluster. The fuel-level sensor is one of the few that are analog in my car.
from 2 to 8 volts. with resistors yes, I know.
but I don’t know anything else. I have a very difficult path .
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Try what I recommend, use an ardunio to get the data from the sensors and pass the data to the VIM3, I once did the same with just an arduino to measure my PC temperature and other stats,
I wasn’t measuring a car but you do get the point
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