I feel like this is a true beginners problem, but I fail to see what I am doing wrong here:

I have a SIP switch connected to port A of an Atmega32 and I cannot read correct values from the port. Here is the relevant part of the circuit diagrm:

enter image description here

Now in code, I configure port A as input and activate the internal pullups, however I always read the data word I write to the port when configuring the pullups. Measuring the voltage at the pins with a multimeter I read the correct highs and lows according to the position of the single switches.

The rest of my circuit works, SPI communication and all. Still I reproduced the problem with a minimalist example, what could possibly go wrong here?

#include <avr/io.h>

int main(void)
    PORTA = 0xff;
    DDRA = 0xff;
        char bla = PORTA;

I cannot rule out, that I have damaged the port, through misconfiguration and the resulting short circuit. So should my next step be to exchange the controller?


The input available at port <x> is read from PINx. PORTx contains the latched values last set there.

char bla = PINA;
  • 1
    \$\begingroup\$ There is a saying here in Germany that roughly translates to he who can read has clear advantages in life :). Thanks for spotting my mistake so quickly. \$\endgroup\$ – Herr von Wurst Sep 11 '14 at 11:33

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