STM32f429: reading 2.5V issue as soon as I connect the source to the ADC input

[harry123]

Hi 

I'm trying to read a 2.5V signal through internal adc as soon as I connect the signal to the gpio pin of stm there is shift(to positive side)in the signal and also generating the noise upon seeing through oscilloscope.

Also made ground connection.

[Tesla DeLorean]

What pin on what board?

Check the schematic to understand what might be on the pin

Perhaps use a opamp so as not to load the signal.

[harry123]

Pin PA4 

Using voltage divider to lower the voltage from 46V to 2.5V and giving the signal to Stm.