Datasheet

8197C–AVR–05/11

ATtiny261A/461A/861A

The following code examples show how to do an atomic write of the TCNT1 register contents.

Writing any of the OCR1A/B/C/D registers can be done by using the same principle.

Note: See “Code Examples” on page 6.

The assembly code example requires that the r17:r16 register pair contains the value to be writ-

ten to TCNT1.

Assembly Code Example

TIM1_WriteTCNT1:

; Save global interrupt flag

in r18,SREG

; Disable interrupts

cli

; Set TCNT1 to r17:r16

out TC1H,r17

out TCNT1,r16

; Restore global interrupt flag

out SREG,r18

ret

C Code Example

void TIM1_WriteTCNT1( unsigned int i )

{

unsigned char sreg;

unsigned int i;

/* Save global interrupt flag */

sreg = SREG;

/* Disable interrupts */

_CLI();

/* Set TCNT1 to i */

TC1H = (i >> 8);

TCNT1 = (unsigned char)i;

/* Restore global interrupt flag */

SREG = sreg;

}