Datasheet

ATmega8A [DATASHEET]

8159E–AVR–02/2013

The following code examples show how to do an atomic read of the TCNT1 Register contents. Reading any of the

OCR1A/B or ICR1 Registers can be done by using the same principle.

Note: 1. See “About Code Examples” on page 6.

The assembly code example returns the TCNT1 value in the r17:r16 Register pair.

Assembly Code Example

(1)

TIM16_ReadTCNT1:

; Save Global Interrupt Flag

in r18,SREG

; Disable interrupts

cli

; Read TCNT1 into r17:r16

in r16,TCNT1L

in r17,TCNT1H

; Restore Global Interrupt Flag

out SREG,r18

ret

C Code Example

(1)

unsigned int TIM16_ReadTCNT1( void )

{

unsigned char sreg;

unsigned int i;

/* Save Global Interrupt Flag */

sreg = SREG;

/* Disable interrupts */

_CLI();

/* Read TCNT1 into i */

i = TCNT1;

/* Restore Global Interrupt Flag */

SREG = sreg;

return i;

}