ATMEGA8 datasheet(79/303 Pages) ATMEL

79 / 303 page

ATmega8(L)

2486M–AVR–12/03

The following code examples show how to do an atomic write of the TCNT1 Register

contents. Writing any of the OCR1A/B or ICR1 Registers can be done by using the

same principle.

Note:

1. The example code assumes that the part specific header file is included.

The assembly code example requires that the r17:r16 Register pair contains the value to

be written to TCNT1.

Reusing the Temporary High

Byte Register

If writing to more than one 16-bit register where the High byte is the same for all regis-

ters written, then the High byte only needs to be written once. However, note that the

same rule of atomic operation described previously also applies in this case.

Assembly Code Example

(1)

TIM16_WriteTCNT1:

; Save Global Interrupt Flag

r18,SREG

; Disable interrupts

cli

; Set TCNT1 to r17:r16

out TCNT1H,r17

out TCNT1L,r16

; Restore Global Interrupt Flag

out SREG,r18

ret

C Code Example

(1)

void TIM16_WriteTCNT1( unsigned int i )

{

unsigned char sreg;

unsigned int i;

/* Save Global Interrupt Flag */

sreg = SREG;

/* Disable interrupts */

_CLI();

/* Set TCNT1 to i */

TCNT

1 = i;

/* Restore Global Interrupt Flag */

SREG = sreg;

}

ATMEGA8 Datasheet(PDF) 79 Page - ATMEL Corporation

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