Datasheet

Figure 16-9. Timer/Counter Timing Diagram, with Prescaler (f
clk_I/O
/8)
TOVn
TCNTn MAX - 1 MAX BOTTOM BOTTOM + 1
clk
I/O
clk
Tn
(clk
I/O
/8)
Note: The “n” in the register and bit names indicates the device number (n = 0 for Timer/Counter 0), and
the “x” indicates Output Compare unit (A/B).
The next figure shows the setting of OCF0B in all modes and OCF0A in all modes (except CTC mode
and PWM mode where OCR0A is TOP).
Figure 16-10. Timer/Counter Timing Diagram, Setting of OCF0x, with Prescaler (f
clk_I/O
/8)
OCFnx
OCRnx
TCNTn
OCRnx Value
OCRnx - 1 OCRnx OCRnx + 1 OCRnx + 2
clk
I/O
clk
Tn
(clk
I/O
/8)
Note: The “n” in the register and bit names indicates the device number (n = 0 for Timer/Counter 0), and
the “x” indicates Output Compare unit (A/B).
The next figure shows the setting of OCF0A and the clearing of TCNT0 in CTC mode and fast PWM
mode where OCR0A is TOP.
Figure 16-11. Timer/Counter Timing Diagram, Clear Timer on Compare Match mode, with Prescaler (f
clk_I/O
/8)
OCFnx
OCRnx
TCNTn
(CTC)
TOP
TOP - 1 TOP BOTTOM BOTTOM + 1
clk
I/O
clk
Tn
(clk
I/O
/8)
Atmel ATmega644A [DATASHEET]
Atmel-42716C-ATmega644A_Datasheet_Complete-10/2016
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