Datasheet

197
ATmega640/1280/1281/2560/2561
2549K–AVR–01/07
The mechanisms for reading TCNT2, OCR2A, OCR2B, TCCR2A and TCCR2B are dif-
ferent. When reading TCNT2, the actual timer value is read. When reading OCR2A,
OCR2B, TCCR2A and TCCR2B the value in the temporary storage register is read.
TIMSK2 – Timer/Counter2
Interrupt Mask Register
• Bit 2 – OCIE2B: Timer/Counter2 Output Compare Match B Interrupt Enable
When the OCIE2B bit is written to one and the I-bit in the Status Register is set (one),
the Timer/Counter2 Compare Match B interrupt is enabled. The corresponding interrupt
is executed if a compare match in Timer/Counter2 occurs, i.e., when the OCF2B bit is
set in the Timer/Counter 2 Interrupt Flag Register – TIFR2.
• Bit 1 – OCIE2A: Timer/Counter2 Output Compare Match A Interrupt Enable
When the OCIE2A bit is written to one and the I-bit in the Status Register is set (one),
the Timer/Counter2 Compare Match A interrupt is enabled. The corresponding interrupt
is executed if a compare match in Timer/Counter2 occurs, i.e., when the OCF2A bit is
set in the Timer/Counter 2 Interrupt Flag Register – TIFR2.
• Bit 0 – TOIE2: Timer/Counter2 Overflow Interrupt Enable
When the TOIE2 bit is written to one and the I-bit in the Status Register is set (one), the
Timer/Counter2 Overflow interrupt is enabled. The corresponding interrupt is executed if
an overflow in Timer/Counter2 occurs, i.e., when the TOV2 bit is set in the
Timer/Counter2 Interrupt Flag Register – TIFR2.
TIFR2 – Timer/Counter2
Interrupt Flag Register
• Bit 2 – OCF2B: Output Compare Flag 2 B
The OCF2B bit is set (one) when a compare match occurs between the Timer/Counter2
and the data in OCR2B – Output Compare Register2. OCF2B is cleared by hardware
when executing the corresponding interrupt handling vector. Alternatively, OCF2B is
cleared by writing a logic one to the flag. When the I-bit in SREG, OCIE2B
(Timer/Counter2 Compare match Interrupt Enable), and OCF2B are set (one), the
Timer/Counter2 Compare match Interrupt is executed.
• Bit 1 – OCF2A: Output Compare Flag 2 A
The OCF2A bit is set (one) when a compare match occurs between the Timer/Counter2
and the data in OCR2A – Output Compare Register2. OCF2A is cleared by hardware
when executing the corresponding interrupt handling vector. Alternatively, OCF2A is
cleared by writing a logic one to the flag. When the I-bit in SREG, OCIE2A
(Timer/Counter2 Compare match Interrupt Enable), and OCF2A are set (one), the
Timer/Counter2 Compare match Interrupt is executed.
Bit 76543 2 1 0
(0x70) – – – – – OCIE2B OCIE2A TOIE2 TIMSK2
Read/Write R R R R R R/W R/W R/W
Initial Value 0 0 0 0 0 0 0 0
Bit 76543210
0x17 (0x37) –––––OCF2BOCF2ATOV2TIFR2
Read/WriteRRRRRR/W R/W R/W
Initial Value00000000