105
8023F–AVR–07/09
ATmega325P/3250P
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
”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
14.10.5
TIFR0 – Timer/Counter 0 Interrupt Flag Register
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.
14.10.6
GTCCR – General Timer/Counter Control Register
Bit 7 – TSM: Timer/Counter Synchronization Mode
Writing the TSM bit to one activates the Timer/Counter Synchronization mode. In this mode, the
value that is written to the PSR2 and PSR10 bits is kept, hence keeping the corresponding pres-
caler reset signals asserted. This ensures that the corresponding Timer/Counters are halted and
can be configured to the same value without the risk of one of them advancing during configura-
tion. When the TSM bit is written to zero, the PSR2 and PSR10 bits are cleared by hardware,
and the Timer/Counters start counting simultaneously.
Bit
765
4321
0
–
–OCF0A
TOV0
TIFR0
Read/Write
RR
RRRR
R/W
Initial Value
000
0000
0
Bit
7
6
5
4
3
2
1
0
TSM
–
PSR2
PSR10
GTCCR
Read/Write
R/W
R
R/W
Initial Value
0