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AVCC should be very close to the Vcc supply voltage.? If that is at 4.6 then either your Vcc is at

4.6 or something is dragging AVCC down.? Normally this pin is unconnected, but if you want

best repeat measurements from the ADC you can add a filter to the AVCC lead.

ADC reference for analog-to-digital voltage conversions is the built in 1.2 volt AREF potential.

If the AREF is not correct then the ADC measurements will be inaccurate.

If using ADC inputs to detect specific voltages you can use a high impedance DC meter

to measure the actual voltage to see if they are within a range specified by the software.

Arv
_._

On Sat, Dec 9, 2017 at 10:23 AM, <ondrej.briatka@...> wrote:

Problem with encoder - try to check voltage at pin AVCC of ATmega. It should be close to 5V.
After "Unreliable microcontroller start-up" modification, I had only 4,6V on AVCC that caused bad decoding of buttons inputs (3 buttons + resistors make a different voltages on A/D input, software compares it to reference AVCC).
Inductors 100uH has quite high resistance of 7 ohm that means voltage drop on ATmega pins.