
112
8154B–AVR–07/09
ATmega16A
A FOC1A/FOC1B strobe will not generate any interrupt nor will it clear the timer in Clear Timer
on Compare match (CTC) mode using OCR1A as TOP.
The FOC1A/FOC1B bits are always read as zero.
Bit 1:0 – WGM11:0: Waveform Generation Mode
Combined with the WGM13:2 bits found in the TCCR1B Register, these bits control the counting
sequence of the counter, the source for maximum (TOP) counter value, and what type of wave-
form generation to be used, see
Table 16-5. Modes of operation supported by the Timer/Counter
unit are: Normal mode (counter), Clear Timer on Compare match (CTC) mode, and three types
Note:
1. The CTC1 and PWM11:0 bit definition names are obsolete. Use the
WGM12:0 definitions. However, the functionality and
location of these bits are compatible with previous versions of the timer.
16.11.2
TCCR1B – Timer/Counter1 Control Register B
Bit 7 – ICNC1: Input Capture Noise Canceler
Setting this bit (to one) activates the Input Capture Noise Canceler. When the Noise Canceler is
activated, the input from the Input Capture Pin (ICP1) is filtered. The filter function requires four
successive equal valued samples of the ICP1 pin for changing its output. The Input Capture is
therefore delayed by four Oscillator cycles when the Noise Canceler is enabled.
Table 16-5.
Waveform Generation Mode Bit Descript
ionMode
WGM13
WGM12
(CTC1)
WGM11
(PWM11)
WGM10
(PWM10)
Timer/Counter Mode of Operation
TOP
Update of
OCR1
x
TOV1 Flag Set
on
00
0
Normal
0xFFFF
Immediate
MAX
10
0
1
PWM, Phase Correct, 8-bit
0x00FF
TOP
BOTTOM
20
0
1
0
PWM, Phase Correct, 9-bit
0x01FF
TOP
BOTTOM
30
0
1
PWM, Phase Correct, 10-bit
0x03FF
TOP
BOTTOM
40
1
0
CTC
OCR1A
Immediate
MAX
50
1
0
1
Fast PWM, 8-bit
0x00FF
BOTTOM
TOP
60
1
0
Fast PWM, 9-bit
0x01FF
BOTTOM
TOP
70
1
Fast PWM, 10-bit
0x03FF
BOTTOM
TOP
81
0
PWM, Phase and Frequency Correct
ICR1
BOTTOM
91
0
1
PWM, Phase and Frequency Correct
OCR1A
BOTTOM
10
1
0
1
0
PWM, Phase Correct
ICR1
TOP
BOTTOM
11
1
0
1
PWM, Phase Correct
OCR1A
TOP
BOTTOM
12
1
0
CTC
ICR1
Immediate
MAX
13
1
0
1
Reserved
–
14
1
0
Fast PWM
ICR1
BOTTOM
TOP
15
1
Fast PWM
OCR1A
BOTTOM
TOP
Bit
7
6
5
4
3
2
1
0
ICNC1
ICES1
–
WGM13
WGM12
CS12
CS11
CS10
TCCR1B
Read/Write
R/W
R
R/W
Initial Value
0