I have a water level sensor. It assumes a state of 0 - 190 ohms. I want to read the value on Arduino Goga R1. I use A0. In order not to exceed the current for the pin is 8mA, I need a minimum of 625 ohms. The divider according to the drawing gives 625 ohms. But I have only a range of 0V - 1.5V on pin A0. This limits the accuracy of the reading. What system should be built to measure 0 - 190 ohms, max 8mA, scale 0-5V?
I don't have any experience with the Giga, but I think you could change the ADC reference voltage, so that instead of using a 5V range the ADC uses a lower range. What are the options for analogReference()?
The 8mA specification is the maximum output current for the digital pins, so it does not apply to your application.
The analog input pins are designed for a maximum of 3.3V NOT 5V, so your resolution is only cut in half. If you set the resolution to 16 bits you still have 15 bits of resolution.