Getting Started

Chapter 7: Microcontroller Interrupts and Timers

MSK = (1<<PCIE0)|(1<<PCIE1);

ined by the address ‘vector’

f the data book. We use the following code to access

SIGNAL(SIG_PIN_CHANGE1)

ctory in signal.h, which defines

piler. We’ll get to

specifically for a particular microcontroller and a

articular C compiler and it is not portable like most of C. The original Butterfly

#pragma vector = PCINT0_vect

__interrupt void PCINT0_interrupt(void)

mething

}

EIFR = (1<<PCIF0)|(1<<PCIF1);
EI

The program will jump to the interrupt routine when the interrupt is triggered, but
where is the interrupt routine? The location is determ
listed in Table 22, page 47 o
the PCI1 interrupt:

{
// Do something
}

SIGNAL is defined in the WinAVR include dire
some macros to handle interrupt functions using the gcc com
macros later.
Interrupt handling is defined
p
code was built using the IAR C compiler and uses this format for interrupts:

{

// Do so

We’ll get to pragmas later. IAR handles interrupts one-way and WinAVR does it
another.

Let’s review:

• We setup a register, PCMSK1, to indicate which port B pins can cause
  interrupts.


• We setup the External Interrupt Mask Register, EIMSK, and External
  Interrupt Flag Register, to enable the PCI1 interrupt.


• We provided the SIGNAL(SIG_PIN_CHANGE1) code to be called when
  the interrupt occurs.