Datasheet
ATmega164A/PA/324A/PA/644A/PA/1284/P
2018 Microchip Technology Inc. Data Sheet Complete DS40002070A-page 138
Note: 1. The CTCn and PWMn1:0 bit definition names are obsolete. Use the WGMn2:0 definitions. However, the functionality
and location of these bits are compatible with previous versions of the timer.
16.12.2 TCCRnB – Timer/Counter n Control Register B
• Bit 7 – ICNCn: 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 (ICPn) is filtered. The filter function requires four successive equal valued
samples of the ICPn pin for changing its output. The Input Capture is therefore delayed by four Oscillator cycles
when the noise canceler is enabled.
• Bit 6 – ICESn: Input Capture Edge Select
This bit selects which edge on the Input Capture pin (ICPn) that is used to trigger a capture event. When the
ICESn bit is written to zero, a falling (negative) edge is used as trigger, and when the ICESn bit is written to one,
a rising (positive) edge will trigger the capture.
When a capture is triggered according to the ICESn setting, the counter value is copied into the Input Capture
Register (ICRn). The event will also set the Input Capture Flag (ICFn), and this can be used to cause an Input
Capture Interrupt, if this interrupt is enabled.
Table 16-5. Waveform Generation mode bit description
(1)
Mode WGMn3
WGMn2
(CTCn)
WGMn1
(PWMn1)
WGMn0
(PWMn0)
Timer/Counter mode of
operation
TOP
Update of
OCRn
x at
TOVn flag
set on
0 0 0 0 0 Normal 0xFFFF Immediate MAX
1 0 0 0 1 PWM, Phase Correct, 8-bit 0x00FF TOP BOTTOM
2 0 0 1 0 PWM, Phase Correct, 9-bit 0x01FF TOP BOTTOM
3 0 0 1 1 PWM, Phase Correct, 10-bit 0x03FF TOP BOTTOM
4 0 1 0 0 CTC OCRnA Immediate MAX
5 0 1 0 1 Fast PWM, 8-bit 0x00FF BOTTOM TOP
6 0 1 1 0 Fast PWM, 9-bit 0x01FF BOTTOM TOP
7 0 1 1 1 Fast PWM, 10-bit 0x03FF BOTTOM TOP
8 1 0 0 0
PWM, Phase and Frequency
Correct
ICRn BOTTOM BOTTOM
9 1 0 0 1
PWM, Phase and Frequency
Correct
OCRnA BOTTOM BOTTOM
10 1 0 1 0 PWM, Phase Correct ICRn TOP BOTTOM
11 1 0 1 1 PWM, Phase Correct OCRnA TOP BOTTOM
12 1 1 0 0 CTC ICRn Immediate MAX
13 1 1 0 1 (Reserved) – – –
14 1 1 1 0 Fast PWM ICRn BOTTOM TOP
15 1 1 1 1 Fast PWM OCRnA BOTTOM TOP
Bit 7654 3210
(0x81) ICNCn ICESn
– WGMn3 WGMn2 CSn2 CSn1 CSn0 TCCRnB
Read/Write R/W R/W R R/W R/W R/W R/W R/W
Initial Value 0 0 0 0 0 0 0 0