Re: [avr-gcc-list] Heli reding inputs from PORTC

[J.C. Wren]

   If you're trying to read the I/O pins, you need to read PINC. PORTC 
is the value that will be output on the port pins for any pins that are 
outputs, or control whether the pullups are enabled for pins that are 
inputs.  Read and writing PORTC is perfectly legal, just probably not 
what you want.

   --jc

Helix wrote:

> Hello,
> I am trying to use an input, but seems thatI'm doing something wrong here.
> I tried to turn on some ouput (where I connected a led thatI already tested
> as output)
> when I read an input high.
> My output is always off (seems that I'm unable to read input from portc.
> What am I doing wrong here ?
> TIA
>
> My CPU is AT90S8515
>
> int main()
> {
> unsigned int i;
> unsigned char c ;
>
> // enable all bits of PORTA as outputs
> DDRA = 0xff;
>
> // enable all bits of PORTC as inputs
> DDRC = 0x00;
>
>    while (1) {
>
>  if (PORTC)
>   PORTA = 0xFF ;
>  else
>   PORTA = 0 ;
> }
>
> return 0;
> }
>
>
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