Datasheet

101
ATmega48PA/88PA/168PA [DATASHEET]
9223F–AVR–04/14
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.
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;
}
Note: 1. Section 6. “About Code Examples” on page 7
For I/O registers located in extended I/O map, “IN”, “OUT”, “SBIS”, “SBIC”, “CBI”, and “SBI” instructions
must be replaced with instructions that allow access to extended I/O. Typically “LDS” and “STS” combined
with “SBRS”, “SBRC”, “SBR”, and “CBR”.