ATMEGA8L ATMEL [ATMEL Corporation], ATMEGA8L Datasheet - Page 79

• Manufacturer Part Number: ATMEGA8L
• Description: 8-bit AVR with 8K Bytes In-System Programmable Flash
• Manufacturer: ATMEL [ATMEL Corporation]

Reusing the Temporary High
Byte Register
2486M–AVR–12/03
The following code examples show how to do an atomic write of the TCNT1 Register
contents. Writing any of the OCR1A/B or ICR1 Registers can be done by using the
same principle.
Note:
The assembly code example requires that the r17:r16 Register pair contains the value to
be written to TCNT1.
If writing to more than one 16-bit register where the High byte is the same for all regis-
ters written, then the High byte only needs to be written once. However, note that the
same rule of atomic operation described previously also applies in this case.
Assembly Code Example
C Code Example
TIM16_WriteTCNT1:
void TIM16_WriteTCNT1( unsigned int i )
{
}
; Save Global Interrupt Flag
in r18,SREG
; Disable interrupts
cli
; Set TCNT1 to r17:r16
out TCNT1H,r17
out TCNT1L,r16
; Restore Global Interrupt Flag
out SREG,r18
ret
unsigned char sreg;
unsigned int i;
/* Save Global Interrupt Flag */
sreg = SREG;
/* Disable interrupts */
_CLI();
/* Set TCNT1 to i */
TCNT1 = i;
/* Restore Global Interrupt Flag */
SREG = sreg;
1. The example code assumes that the part specific header file is included.
(1)
(1)
ATmega8(L)
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