ATMEGA329_071 Datasheet, PDF (26/29 Pages) ATMEL Corporation – 8-bit Microcontroller with In-System Programmable Flash

10.3 ATmega649
10.3.1
ATmega649 rev. A
• Interrupts may be lost when writing the timer registers in the asynchronous timer
1. Interrupts may be lost when writing the timer registers in the asynchronous timer
If one of the timer registers which is synchronized to the asynchronous timer2 clock is writ-
ten in the cycle before a overflow interrupt occurs, the interrupt may be lost.
Problem Fix/Wortkaround
Always check that the Timer2 Timer/Counter register, TCNT2, does not have the value 0xFF
before writing the Timer2 Control Register, TCCR2, or Output Compare Register, OCR2.
10.4 ATmega6490
10.4.1
ATmega6490 rev. A
• Interrupts may be lost when writing the timer registers in the asynchronous timer
1. Interrupts may be lost when writing the timer registers in the asynchronous timer
If one of the timer registers which is synchronized to the asynchronous timer2 clock is writ-
ten in the cycle before a overflow interrupt occurs, the interrupt may be lost.
Problem Fix/Wortkaround
Always check that the Timer2 Timer/Counter register, TCNT2, does not have the value 0xFF
before writing the Timer2 Control Register, TCCR2, or Output Compare Register, OCR2.
26 ATmega329/3290/649/6490
2552JS–AVR–08/07