To Next Page

To Previous Page

116

2467S–AVR–07/09

ATmega128

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

Reading any of the OCRnA/B/C or ICRn Registers can be done by using the same principle.

Note: 1. See “About Code Examples” on page 9.

The assembly code example returns the TCNTn value in the r17:r16 register pair.

Assembly Code Example

(1)

TIM16_ReadTCNTn:

; Save global interrupt flag

in r18,SREG

; Disable interrupts

cli

; Read TCNTn into r17:r16

in r16,TCNTnL

in r17,TCNTnH

; Restore global interrupt flag

out SREG,r18

ret

C Code Example

(1)

unsigned int TIM16_ReadTCNTn( void )

{

unsigned char sreg;

unsigned int i;

/* Save global interrupt flag */

sreg = SREG;

/* Disable interrupts */

__disable_interrupt();

/* Read TCNTn into i */

i = TCNTn;

/* Restore global interrupt flag */

SREG = sreg;

return i;

}

Atmel ATmega128 User Manual

Questions and Answers: