Atmega32(l) – Rainbow Electronics ATmega32L User Manual
Page 88
88
ATmega32(L)
2503C–AVR–10/02
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. The example code assumes that the part specific header file is included.
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;
}