atmega32u4-16mu ATMEL Corporation, atmega32u4-16mu Datasheet - Page 110

• Manufacturer Part Number: atmega32u4-16mu
• Description: Atmega32u4 8-bit Avr Microcontroller With 32k Bytes Of Isp Flash And Usb Controller
• Manufacturer: ATMEL Corporation

110
ATmega32U4
Note:
The assembly code example returns the TCNTn value in the r17:r16 register pair.
The following code examples show how to do an atomic write of the TCNTn Register contents.
Writing any of the OCRnA/B/C or ICRn Registers can be done by using the same principle.
C Code Example
Assembly Code Example
TIM16_ReadTCNTn:
unsigned int TIM16_ReadTCNTn( void )
{
}
; 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
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 7.
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7766A–AVR–03/08