ATMEGA161-8PI Atmel, ATMEGA161-8PI Datasheet - Page 52

• Manufacturer Part Number: ATMEGA161-8PI
• Description: IC AVR MCU 16K 8MHZ IND 40-DIP
• Manufacturer: Atmel
• Series: AVR® ATmegar

Specifications of ATMEGA161-8PI

• Core Processor: AVR
• Core Size: 8-Bit
• Speed: 8MHz
• Connectivity: SPI, UART/USART
• Peripherals: POR, PWM, WDT
• Number Of I /o: 35
• Program Memory Size: 16KB (8K x 16)
• Program Memory Type: FLASH
• Eeprom Size: 512 x 8
• Ram Size: 1K x 8
• Voltage - Supply (vcc/vdd): 4 V ~ 5.5 V
• Oscillator Type: External
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 40-DIP (0.600", 15.24mm)
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Data Converters: -
• Other names: ATMEGA1618PI

Timer/Counter1 Control
Register B – TCCR1B
52
ATmega161(L)
• Bits 1..0
These bits select PWM operation of Timer/Counter1 as specified in Table 15. This mode
is described on page 55.
Table 15. PWM Mode Select
• Bit 7
When the ICNC1 bit is cleared (zero), the Input Capture trigger noise canceler function
is disabled. The Input Capture is triggered at the first rising/falling edge sampled on the
ICP (Input Capture pin) as specified. When the ICNC1 bit is set (one), four successive
samples are measured on the ICP (Input Capture pin), and all samples must be high/low
according to the Input Capture trigger specification in the ICES1 bit. The actual sampling
frequency is XTAL clock frequency.
• Bit 6
While the ICES1 bit is cleared (zero), the Timer/Counter1 contents are transferred to the
Input Capture Register (ICR1) on the falling edge of the Input Capture pin (ICP). While
the ICES1 bit is set (one), the Timer/Counter1 contents are transferred to the Input Cap-
ture Register (ICR1) on the rising edge of the Input Capture pin (ICP).
• Bits 5, 4
These bits are reserved bits in the ATmega161 and always read as zero.
• Bit 3
When the CTC1 control bit is set (one), the Timer/Counter1 is reset to $0000 in the clock
cycle after a compareA match. If the CTC1 control bit is cleared, Timer/Counter1 contin-
ues counting and is unaffected by a compare match. When a prescaling of 1 is used and
the Compare A Register is set to C, the timer will count as follows if CTC1 is set:
... | C-1 | C | 0 | 1 | ...
When the prescaler is set to divide by 8, the timer will count like this:
... | C-1, C-1, C-1, C-1, C-1, C-1, C-1, C-1 | C, C, C, C, C, C, C, C | 0, 0, 0, 0, 0, 0, 0, 0 | ...
In PWM mode, this bit has a different function. If the CTC1 bit is cleared in PWM mode,
the Timer/Counter1 acts as an up/down counter. If the CTC1 bit is set (one), the
Timer/Counter wraps when it reaches the TOP value. Refer to page 55 for a detailed
description.
Bit
$2E ($4E)
Read/Write
Initial Value
PWM11
0
0
1
1
–
–
–
ICNC1: Input Capture1 Noise Canceler (4 CKs)
ICES1: Input Capture1 Edge Select
CTC1: Clear Timer/Counter1 on Compare Match
–
–
PWM11, PWM10: Pulse Width Modulator Select Bits
ICNC1
Res: Reserved Bits
R/W
7
0
PWM10
0
1
0
1
ICES1
R/W
6
0
Description
PWM operation of Timer/Counter1 is disabled.
Timer/Counter1 is an 8-bit PWM.
Timer/Counter1 is a 9-bit PWM.
Timer/Counter1 is a 10-bit PWM.
R
5
–
0
R
4
–
0
CTC1
R/W
3
0
CS12
R/W
2
0
CS11
R/W
1
0
CS10
R/W
0
0
1228D–AVR–02/07
TCCR1B