External interrupts enabling (code understanding)

Projects Programming
1

Hi there!
can anyone please help me to understand these lines which enables the External interrupts on Arduino mega 2560?

  PCICR |= (1 << PCIE0);   
  PCMSK0 |= (1 << PCINT0); 
  PCMSK0 |= (1 << PCINT1);  
  PCMSK0 |= (1 << PCINT2);  
  PCMSK0 |= (1 << PCINT3);

I m not able to understand the purpose of <<and |= in PCMSK0 |= 1 << PCINT0.
I know its a stupid question but Im a newbie.
Bundle of thanks

2

Look up Bitwise Operators and Assignment Operators in Code/Statements/Variables/Operators

3

Whandall:
Look up Bitwise Operators and Assignment Operators in Code/Statements/Variables/Operators

I know the working of bit shifts and assignment operators. but when it comes to PCMSK0 |= 1 << PCINT0 I dont know how PCINT0 is shifted left when this bit present in PCICR register while we are bitwise ORing it with PCMSK0 register.

4

Sorry for the misunderstanding, as you not stated to be familiar with the operators.

It is the 1 that is shifted to the position named PCINT0.
Then it is ored to the mask-register content and written back.

6

Thanks All. I get the point :slight_smile: Thanks again.