ATMEGA48 Datasheet, PDF (129/377 Pages) ATMEL Corporation – 8-bit Microcontroller with 8K Bytes In-System Programmable Flash

ATmega48/88/168
Figure 16-13 shows the same timing data, but with the prescaler enabled.
Figure 16-13. Timer/counter timing diagram, with prescaler (f_{clk_I/O}/8).
clk _I/O
clk _Tn
(clk_I/O/8)
TCNTn
(CTC and FPWM)
TCNTn
(PC and PFC PWM)
TOVn (FPWM)
and ICF n(if used
as TOP)
OCRnx
(update at TOP)
TOP - 1
TOP - 1
TOP
TOP
Old OCRnx value
BOTTOM
TOP - 1
BOTTOM + 1
TOP - 2
New OCRnx value
2545T–AVR–05/11
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