Datasheet

Note: The “n” in the register and bit names indicates the device number (n = 1 for Timer/Counter 1), and
the “x” indicates Output Compare unit (A/B).
The next figure shows the count sequence close to TOP in various modes. When using phase and
frequency correct PWM mode the OCR1x Register is updated at BOTTOM. The timing diagrams will be
the same, but TOP should be replaced by BOTTOM, TOP-1 by BOTTOM+1 and so on. The same
renaming applies for modes that set the TOV1 Flag at BOTTOM.
Figure 16-12. Timer/Counter Timing Diagram, no Prescaling.
TOVn (FPWM)
and ICFn (if used
as TOP)
OCRnx
(Update at TOP)
TCNTn
(CTC and FPWM)
TCNTn
(PC and PFC PWM)
TOP - 1 TOP TOP - 1 TOP - 2
Old OCRnx Value
New OCRnx Value
TOP - 1 TOP BOTTOM BOTTOM + 1
clk
Tn
(clk
I/O
/1)
clk
I/O
Note: The “n” in the register and bit names indicates the device number (n = 1 for Timer/Counter 1), and
the “x” indicates Output Compare unit (A/B).
The next figure shows the same timing data, but with the prescaler enabled.
Figure 16-13. Timer/Counter Timing Diagram, with Prescaler (f
clk_I/O
/8)
TOVn (FPWM)
and ICFn (if used
as TOP)
OCRnx
(Update at TOP)
TCNTn
(CTC and FPWM)
TCNTn
(PC and PFC PWM)
TOP - 1
TOP TOP - 1 TOP - 2
Old OCRnx Value New OCRnx Value
TOP - 1 TOP 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 = 1 for Timer/Counter 1), and
the “x” indicates Output Compare unit (A/B).
16.14. Register Description
Atmel ATmega16M1/32M1/64M1 [DATASHEET]
Atmel-8209F-ATmega16M1/32M1/64M1_Datasheet_Complete-10/2016
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