Custom Interrupts - AVR

Target AVR Processor ( ATMEGA8, 16, 32 )

(Note: For other AVR devices you may have to refer to the device datasheet to obtain the correct code)

USART Receive

The Flowcode RS232 component can be used to set the Baud rate and configure the mode of operation, and the ReceiveRS232Char function can be used in the handler macro to read the data (clearing the interrupt).

Enable code:

UCSRB |= ((1 << RXCIE) | (1 << RXEN)); // enable USART receiver and receive interrupts

Disable code:

UCSRB &= ~(1 << RXCIE); // disable USART receive interrupts

Handler code:

ISR(USART_RXC_vect) // USART receive vector

{

FCM_%n(); // Call Flowcode Macro

}

Analogue Comparator

Enable code:

SFIOR &= ~(1 << ACME); // disable multiplexer input

ACSR |= (1 << ACIE); // enable comparator interrupts - interrupt when comparator output toggles

Disable code:

ACSR &= ~(1 << ACIE); // disable comparator interrupts

Handler code:

ISR(ANA_COMP_vect) // analogue comparator interrupt vector

{

FCM_%n(); // Call Flowcode Macro

}

The state of the comparator input can be read into a Flowcode variable 'compstate' with the following C code line:

FCV_COMPSTATE = ACSR & (1 << ACO);

Timer1 Rollover

Enable code:

TCCR1B = 0x45; // positive edge trigger with no noise canceler, prescaler = /1024

TIMSK |= (1 << TICIE1); // enable input capture interrupts

Disable code:

TIMSK &= ~(1 << TICIE1); // disable input capture interrupts

Handler code:

ISR(TIMER1_CAPT_vect) // input capture vector

{

FCM_%n(); // Call Flowcode Macro

}

The captured 16-bit count value can be read into a Flowcode variable 'captval' with the following C code line:

FCV_CAPTVAL = ICR1;

** captval must be declared as an integer variable **