Datasheet

101
2586D–AVR–02/06
ATtiny25/45/85
16.2.4 OCR1A – Timer/Counter1 Output Compare RegisterA
The output compare register A is an 8-bit read/write register.
The Timer/Counter Output Compare Register A contains data to be continuously compared with
Timer/Counter1. Actions on compare matches are specified in TCCR1. A compare match does
only occur if Timer/Counter1 counts to the OCR1A value. A software write that sets TCNT1 and
OCR1A to the same value does not generate a compare match.
A compare match will set the compare interrupt flag OCF1A after a synchronization delay follow-
ing the compare event.
16.2.5 OCR1C – Timer/Counter1 Output Compare Register C
The Output Compare Register B - OCR1B from ATtiny15 is replaced with the output compare
register C - OCR1C that is an 8-bit read/write register. This register has the same function as the
Output Compare Register B in ATtiny15.
The Timer/Counter Output Compare Register C contains data to be continuously compared with
Timer/Counter1. A compare match does only occur if Timer/Counter1 counts to the OCR1C
value. A software write that sets TCNT1 and OCR1C to the same value does not generate a
compare match. If the CTC1 bit in TCCR1 is set, a compare match will clear TCNT1.
16.2.6 TIMSK – Timer/Counter Interrupt Mask Register
• Bit 7 - Res: Reserved Bit
This bit is a reserved bit in the ATtiny25/45/85 and always reads as zero.
• Bit 6 - OCIE1A: Timer/Counter1 Output Compare Interrupt Enable
When the OCIE1A bit is set (one) and the I-bit in the Status Register is set (one), the
Timer/Counter1 Compare MatchA, interrupt is enabled. The corresponding interrupt at vector
$003 is executed if a compare matchA occurs. The Compare Flag in Timer/Counter1 is set (one)
in the Timer/Counter Interrupt Flag Register.
• Bit 2 - TOIE1: Timer/Counter1 Overflow Interrupt Enable
When the TOIE1 bit is set (one) and the I-bit in the Status Register is set (one), the
Timer/Counter1 Overflow interrupt is enabled. The corresponding interrupt (at vector $004) is
executed if an overflow in Timer/Counter1 occurs. The Overflow Flag (Timer1) is set (one) in the
Timer/Counter Interrupt Flag Register - TIFR.
Bit 76543210
0x2E MSB LSB OCR1A
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
0x2D MSB LSB OCR1C
Read/Write R/W R/W R/W R/W R/W R/W R/W R/W
Initial value 1 1 1 1 1 1 1 1
Bit 7 6 5 4 3 2 1 0
0x39 -OCIE1A
OCIE1B OCIE0A OCIE0B TOIE1 TOIE0 - TIMSK
Read/Write R R/W R/W R R R/W R/W R
Initial value 0 0 0 0 0 0 0 0