ATMEGA649 datasheet(110/375 Pages) ATMEL

110 / 375 page

110

ATmega329/3290/649/6490

2552H–AVR–11/06

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. See “About Code Examples” on page 8.

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 registers

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_WriteTCNT

; Save global interrupt flag

r18,SREG

; Disable interrupts

cli

; Set TCNT

1 to r17:r16

out

TCNT

1H,r17

out

TCNT

1L,r16

; Restore global interrupt flag

out

SREG,r18

ret

C Code Example

(1)

void

TIM16_WriteTCNT

1( unsigned int i )

{

unsigned char

sreg;

unsigned int

/* Save global interrupt flag */

sreg = SREG;

/* Disable interrupts */

__disable_interrupt();

/* Set TCNT

1 to i */

TCNT

1 = i;

/* Restore global interrupt flag */

SREG = sreg;

}

ATMEGA649 Datasheet(PDF) 110 Page - ATMEL Corporation

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