112
7679H–CAN–08/08
AT90CAN32/64/128
12.9.3 Output Compare Register A – OCR0A
The Output Compare Register A contains an 8-bit value that is continuously compared with the
counter value (TCNT0). A match can be used to generate an Output Compare interrupt, or to
generate a waveform output on the OC0A pin.
12.9.4 Timer/Counter0 Interrupt Mask Register – TIMSK0
• Bit 7..2 – Reserved Bits
These are reserved bits for future use.
• Bit 1 – OCIE0A: Timer/Counter0 Output Compare Match A Interrupt Enable
When the OCIE0A bit is written to one, and the I-bit in the Status Register is set (one), the
Timer/Counter0 Compare Match A interrupt is enabled. The corresponding interrupt is executed
if a compare match in Timer/Counter0 occurs, i.e., when the OCF0A bit is set in the
Timer/Counter 0 Interrupt Flag Register – TIFR0.
• 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, i.e., when the TOV0 bit is set in the Timer/Counter 0 Inter-
rupt Flag Register – TIFR0.
12.9.5 Timer/Counter0 Interrupt Flag Register – TIFR0
• Bit 1 – OCF0A: Output Compare Flag 0 A
The OCF0A bit is set (one) when a compare match occurs between the Timer/Counter0 and the
data in OCR0A – Output Compare Register0. OCF0A is cleared by hardware when executing
the corresponding interrupt handling vector. Alternatively, OCF0A is cleared by writing a logic
one to the flag. When the I-bit in SREG, OCIE0A (Timer/Counter0 Compare match Interrupt
Enable), and OCF0A are set (one), the Timer/Counter0 Compare match Interrupt is executed.
• Bit 0 – TOV0: Timer/Counter0 Overflow Flag
The bit TOV0 is set (one) when an overflow occurs in Timer/Counter0. TOV0 is cleared by hard-
ware when executing the corresponding interrupt handling vector. Alternatively, TOV0 is cleared
by writing a logic one to the flag. When the SREG I-bit, TOIE0 (Timer/Counter0 Overflow Inter-
rupt Enable), and TOV0 are set (one), the Timer/Counter0 Overflow interrupt is executed. In
phase correct PWM mode, this bit is set when Timer/Counter0 changes counting direction at
0x00.
Bit 76543210
OCR0A[7:0] OCR0
Read/Write R/W R/W R/W R/W R/W R/W R/W R/W
Initial Value00000000
Bit 76543210
– – – – – – OCIE0A TOIE0 TIMSK0
Read/Write R R R R R R R/W R/W
Initial Value 0 0 0 0 0 0 0 0
Bit 76543210
––––––OCF0A
TOV0 TIFR0
Read/Write R R R R R R R/W R/W
Initial Value00000000
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