After a long afternoon, chasing a fault on my project, I've come to find that I've damaged 2 out of the 6 Analogue Inputs. Their ADC reading doesn't display 0 when grounded, nor a known ADC value from a sensor.

I've identified the problem to the voltage divider sensors that were connected to these particular Analogue Inputs, I've since researched that topic and made some alterations.

I don't suppose by buying a replacement chip, will solve the problem of 2 bad Analogue Inputs? So I can save the hardware and reduce cost?

Thanks in advance for any help you can provide.


  • it is unclear what you are saying ... it seems that you are saying that replacing the atmega328 will not repair the problem ... if that is true, then why do you think so?
    – jsotola
    Feb 13 '18 at 22:58
  • 1
    The analog inputs are wired directly to the ATMega MCU, so replacing it should fix the problem. Is it socketed or soldered to the board? Feb 14 '18 at 2:51
  • new 328s are only about a dollar, but is it worth your time and frustration?
    – dandavis
    Feb 14 '18 at 20:16

If the Analog input of your Arduino Uno is damaged, then unfortunately you have damaged the pins on the ATMEAGA328P chip directly.

As per the schematic below of Arduino Uno R3, the pins A0 to A5 are connected directly on the Pins 23 to 28 of the ATMEGA328P chip.

Arduino UNO R3 Micro-controller Schematic

Therefore if you say that the 2 out of 6 Analog pins have been damaged then the only way to fix that is to replace the ATMEGA328P chip with a new one.

More can be read here about the UNO's hardware design.

PS. When replacing the ATMEGA328P chip, be sure to program the new chip with the Arduino Bootloader so you can upload sketches to it, otherwise it won't work ;)


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