ATMEGA2561V ATMEL [ATMEL Corporation], ATMEGA2561V Datasheet - Page 141

• Manufacturer Part Number: ATMEGA2561V
• Description: 8-bit Microcontroller with 64K/128K/256K Bytes In-System Programmable Flash
• Manufacturer: ATMEL [ATMEL Corporation]

2549K–AVR–01/07
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:
The assembly code example returns the TCNTn value in the r17:r16 register pair.
Assembly Code Example
C Code Example
TIM16_ReadTCNTn:
unsigned int TIM16_ReadTCNTn( void )
{
}
; Save global interrupt flag
in
; Disable interrupts
cli
; Read TCNTn into r17:r16
in
in
; Restore global interrupt flag
out SREG,r18
ret
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;
1. See “About Code Examples” on page 9.
r18,SREG
r16,TCNTnL
r17,TCNTnH
(1)
ATmega640/1280/1281/2560/2561
(1)
141