Datasheet

104
2586N–AVR–04/11
ATtiny25/45/85
• Bits 5:4 – COM1A[1:0]: Comparator A Output Mode, Bits 1 and 0
The COM1A1 and COM1A0 control bits determine any output pin action following a compare
match with compare register A in Timer/Counter1. Output pin actions affect pin PB1 (OC1A).
Since this is an alternative function to an I/O port, the corresponding direction control bit must be
set (one) in order to control an output pin.
In PWM mode, these bits have different functions. Refer to Table 13-1 on page 101 for a
detailed description.
• Bits 3:0 – CS1[3:0]: Clock Select Bits 3, 2, 1, and 0
The Clock Select bits 3, 2, 1, and 0 define the prescaling source of Timer/Counter1.
The Stop condition provides a Timer Enable/Disable function.
Table 13-4. Comparator A Mode Select
COM1A1 COM1A0 Description
0 0 Timer/Counter Comparator A disconnected from output pin OC1A.
0 1 Toggle the OC1A output line.
1 0 Clear the OC1A output line.
1 1 Set the OC1A output line
Table 13-5. Timer/Counter1 Prescale Select
CS13 CS12 CS11 CS10 T/C1 Clock
0 0 0 0 T/C1 stopped
0001PCK
0 0 1 0 PCK/2
0 0 1 1 PCK/4
0 1 0 0 PCK/8
0101CK
0110CK/2
0111CK/4
1000CK/8
1001CK/16
1010CK/32
1011CK/64
1100CK/128
1101CK/256
1110CK/512
1 1 1 1 CK/1024