How to get GroundPI battery voltage readings?

I must be using wrong keywords, but I cannot find it. In want to run GroudPI and Display from 3S battery and I would like to get readings of its voltage. There is the widged in bottom right corner of OSD which I assume is for this purpose. Question is how do I read the voltage? As far as I know RPi does not have analog input, so my guess is I have to connect SPI ADC (I have MCP3008 laying around). Is this is how I do that? If so what are involved settings? Thanks!


You need a INA219 current/voltage sensor and connect it to the i2c port of your groundPi.