Datasheet

Table Of Contents
Bits 1:0 – WGM1n: Waveform Generation Mode [n = 1:0]
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 waveform
generation to be used, refer to the table below. Modes of operation supported by the Timer/Counter unit
are: Normal mode (counter), Clear Timer on Compare match (CTC) mode, and three types of Pulse Width
Modulation (PWM) modes. (See Modes of Operation).
Table 19-5. Waveform Generation Mode Bit Description
Mode
WGM13 WGM12
(CTC1)
WGM11
(PWM11)
WGM10
(PWM10)
Timer/Counter
Mode of Operation
(1)
TOP Update of
OCR1x at
TOV1 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 OCR1A 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
ICR1 BOTTOM BOTTOM
9 1 0 0 1 PWM, Phase and Frequency
Correct
OCR1A BOTTOM BOTTOM
10 1 0 1 0 PWM, Phase Correct ICR1 TOP BOTTOM
11 1 0 1 1 PWM, Phase Correct OCR1A TOP BOTTOM
12 1 1 0 0 CTC ICR1 Immediate MAX
13 1 1 0 1 Reserved - - -
14 1 1 1 0 Fast PWM ICR1 BOTTOM TOP
15 1 1 1 1 Fast PWM OCR1A BOTTOM TOP
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.
Atmel ATmega32A [DATASHEET]
Atmel-8155I-ATmega32A_Datasheet_Complete-08/2016
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