Datasheet

109
2490R–AVR–02/2013
ATmega64(L)
1. Write any value to either of the registers OCR0 or TCCR0.
2. Wait for the corresponding Update Busy Flag to be cleared.
3. Read TCNT0.
• During asynchronous operation, the synchronization of the interrupt flags for the
asynchronous timer takes three processor cycles plus one timer cycle. The timer is therefore
advanced by at least one before the processor can read the timer value causing the setting
of the interrupt flag. The Output Compare pin is changed on the timer clock and is not
synchronized to the processor clock.
TIMSK –
Timer/Counter
Interrupt Mask
Register
• Bit 1 – OCIE0: Timer/Counter0 Output Compare Match Interrupt Enable
When the OCIE0 bit is written to one, and the I-bit in the Status Register is set (one), the
Timer/Counter0 Compare Match interrupt is enabled. The corresponding interrupt is executed if
a Compare Match in Timer/Counter0 occurs, that is, when the OCF0 bit is set in the Timer/Coun-
ter Interrupt Flag Register – TIFR.
• Bit 0 – TOIE0: Timer/Counter0 Overflow Interrupt Enable
When the TOIE0 bit is written to one, and the I-bit in the Status Register is set (one), the
Timer/Counter0 Overflow interrupt is enabled. The corresponding interrupt is executed if an
overflow in Timer/Counter0 occurs, that is, when the TOV0 bit is set in the Timer/Counter Inter-
rupt Flag Register – TIFR.
TIFR – Timer/Counter
Interrupt Flag Register
• Bit 1 – OCF0: Output Compare Flag 0
The OCF0 bit is set (one) when a Compare Match occurs between the Timer/Counter0 and the
data in OCR0 – Output Compare Register0. OCF0 is cleared by hardware when executing the
corresponding interrupt handling vector. Alternatively, OCF0 is cleared by writing a logic one to
the flag. When the I-bit in SREG, OCIE0 (Timer/Counter0 Compare Match Interrupt Enable), and
OCF0 are set (one), the Timer/Counter0 Compare Match Interrupt is executed.
Bit 76543210
0x37 (0x57)
OCIE2 TOIE2 TICIE1 OCIE1A OCIE1B TOIE1 OCIE0 TOIE0 TIMSK
Read/Write R/W R/W R/W R/W R/W R/W R/W R/W
Initial Value 0 0 0 0 0 0 0 0
Bit 76543210
0x36 (0x56)
OCF2 TOV2 ICF1 OCF1A OCF1B TOV1 OCF0 TOV0 TIFR
Read/Write R/W R/W R/W R/W R/W R/W R/W R/W
Initial Value00000000