I have made PORTC.0,PORTC.1,PORTC.2,PORTC.3 as input and set it at high. The remaining pins are set as output and high. Thus all pins of PORTC are high.

Now what I want to check that whenever any pin of PORTC gets low (0), then my function "setDirection()"should be called. For that I have written


but ~PINC condition comes out to be always true, irrespective of any pin of PORTC is low or not. Then I tried this code


this condition never turns out to be true, either PORTC PIN is high or low.

  • \$\begingroup\$ While it has been answered how to check pin state correctly, its not clear what are you trying to achieve. What does setDirection() do exactly? \$\endgroup\$ – Rev1.0 Jul 1 '13 at 7:10
  • \$\begingroup\$ @Rev i was trying to detect that if any of the pin of port c gets low function "setDirection()" should be called which then checks which pin of port c is low and sets direction accordingly... \$\endgroup\$ – shafeeq Jul 4 '13 at 9:54
if ((PINC & 0x0F) != 0x0F) setDirection();

This tests if any of the 4 bits are not high. The tests you tried require that ALL of the bits be low.

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