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I am working on a 3V battery powered arduino project. I need to monitor the battery so that I could send a signal when battery is dying. At first it seemed tricky because the same voltage is being used by the micro-controller but later on I came to know that there is some sort of internal 1.1V reference in Arduino. However I need to use a voltage divider to reduce the voltage. This is the circuit described on the webpage:
PIN_A1 is where the battery voltage is being read. High value resistors have been used to avoid excessive current draw.
My question is - What is the aim of using a voltage divider here?
It has been figured out that voltage divider is bringing the battery voltage within internal voltage reference range i.e. 1.1 V.
(Credit goes to Vladimir)