Matrix user forums

Hi guys,

I would appreciate some help understanding how to read a 12 volt battery level using the ADC inputs. I have experimented with the 5 volt ADC of the variable resistor pot and understand that, but am not sure how to approach the higher voltage input scenario?

Any suggestions would be appreciated.

Thanks
Ted

Hello Ted,

I would use a simple potential divider resistor circuit to drop the 12V down to something you can read directly.

12V
|
10K
|
|- ADC Pin
|
1K
|
GND

This would give you 1/11th of the voltage to the ADC pin.

VOUT = (12V / 11K) * 1K = 1.09V

Changing the resistor values will give you different voltages so the ideal is to take your maximum possible voltage (maybe 14V for a 12V battery) and choose resistor values to give you 5V to your ADC pin. This way you get 5V / 1024 discreet values = 4.88mV resolution.

Hi Benj

Thanks for your solution, will build up a resistor chain on my breadboard and play around with the values.

Regards
Ted

HI Ted ,

if you look at martin's post on this thread he posted a 0 - 15 volt voltmeter

http://www.matrixtsl.com/mmforums/viewt ... 99&p=20326

Steve

Thank you Steve...much appreciated.

Rgds
Ted