ATTINY25-20SUR Atmel, ATTINY25-20SUR Datasheet - Page 92

• Manufacturer Part Number: ATTINY25-20SUR
• Description: MCU AVR 2KB FLASH 20MHZ 8SOIC
• Manufacturer: Atmel
• Series: AVR® ATtinyr

Specifications of ATTINY25-20SUR

• Core Processor: AVR
• Core Size: 8-Bit
• Speed: 20MHz
• Connectivity: USI
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Number Of I /o: 6
• Program Memory Size: 2KB (1K x 16)
• Program Memory Type: FLASH
• Eeprom Size: 128 x 8
• Ram Size: 128 x 8
• Voltage - Supply (vcc/vdd): 2.7 V ~ 5.5 V
• Data Converters: A/D 4x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: *
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

12.3
12.3.1
92
Register Description
ATtiny25/45/85
TCCR1 – Timer/Counter1 Control Register
• Bit 7 – CTC1 : Clear Timer/Counter on Compare Match
When the CTC1 control bit is set (one), Timer/Counter1 is reset to $00 in the CPU clock cycle
after a compare match with OCR1C register value. If the control bit is cleared, Timer/Counter1
continues counting and is unaffected by a compare match.
• Bit 6 – PWM1A: Pulse Width Modulator A Enable
When set (one) this bit enables PWM mode based on comparator OCR1A in Timer/Counter1
and the counter value is reset to $00 in the CPU clock cycle after a compare match with OCR1C
register value.
• 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. Since the output pin action is an alternative
function to an I/O port, the corresponding direction control bit must be set (one) in order to con-
trol an output pin.
In Normal mode, the COM1A1 and COM1A0 control bits determine the output pin actions that
affect pin PB1 (OC1A) as described in
mode.
Table 12-4.
In PWM mode, these bits have different functions. Refer to
description.
Bit
0x30
Read/Write
Initial value
COM1A1
0
0
1
1
CTC1
Comparator A Mode Select
R/W
COM1A0
7
0
0
1
0
1
PWM1A
R/W
6
0
Description
Timer/Counter Comparator A disconnected from output pin OC1A.
Toggle the OC1A output line.
Clear the OC1A output line.
Set the OC1A output line
COM1A1
R/W
5
0
Table
COM1A0
R/W
4
0
12-4. Note that OC1A is not connected in normal
CS13
R/W
3
0
Table 12-1 on page 89
CS12
R/W
2
0
CS11
R/W
1
0
CS10
R/W
0
0
2586M–AVR–07/10
for a detailed
TCCR1