ATMEGA8L ATMEL [ATMEL Corporation], ATMEGA8L Datasheet - Page 94

• Manufacturer Part Number: ATMEGA8L
• Description: 8-bit AVR with 8K Bytes In-System Programmable Flash
• Manufacturer: ATMEL [ATMEL Corporation]

94
ATmega8(L)
Figure 42. Timer/Counter Timing Diagram, Setting of OCF1x, with Prescaler (f
Figure 43 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 43. Timer/Counter Timing Diagram, no Prescaling
Figure 44 shows the same timing data, but with the prescaler enabled.
TCNTn
OCRnx
OCFnx
(PC and PFC PWM)
(clk
and ICFn
(CTC and FPWM)
clk
clk
TOVn
(Update at TOP)
I/O
I/O
Tn
OCRnx
TCNTn
TCNTn
as TOP)
(clk
/8)
clk
clk
I/O
(FPWM)
I/O
Tn
/1)
(if used
OCRnx - 1
TOP - 1
TOP - 1
Old OCRnx Value
OCRnx
OCRnx Value
TOP
TOP
OCRnx + 1
BOTTOM
TOP - 1
New OCRnx Value
2486M–AVR–12/03
OCRnx + 2
BOTTOM + 1
TOP - 2
clk_I/O
/8)