96
4317I–AVR–01/08
AT90PWM2/3/2B/3B
Figure 14-9. Timer/Counter Timing Diagram, with Prescaler (f
clk_I/O
/8)
shows the setting of OCF0B in all modes and OCF0A in all modes except CTC
mode and PWM mode, where OCR0A is TOP.
Figure 14-10. Timer/Counter Timing Diagram, Setting of OCF0x, with Prescaler (f
clk_I/O
/8)
shows the setting of OCF0A and the clearing of TCNT0 in CTC mode and fast
PWM mode where OCR0A is TOP.
Figure 14-11. Timer/Counter Timing Diagram, Clear Timer on Compare Match mode, with Pres-
caler (f
clk_I/O
/8)
14.8
8-bit Timer/Counter Register Description
14.8.1
Timer/Counter Control Register A – TCCR0A
TOVn
TCNTn
MAX - 1
MAX
BOTTOM
1
clk
I/O
clk
Tn
(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)
OCFnx
OCRnx
TCNTn
(CTC)
TOP
TOP - 1
TOP
BOTTOM
1
clk
I/O
clk
Tn
(clk
I/O
/8)
Bit
7
6
5
4
3
2
1
0
COM0A1
COM0A0
COM0B1
COM0B0
–
–
WGM01
WGM00
TCCR0A
Read/Write
R/W
R/W
R/W
R/W
R
R
R/W
R/W
Initial Value
0
0
0
0
0
0
0
0