ATMEGA8515 Datasheet, PDF (91/254 Pages) ATMEL Corporation – 8-bit AVR Microcontroller with 8K Bytes In-System Programmable Flash

2512G–AVR–03/05
ATmega8515(L)
When OC0 is connected to the pin, the function of the COM01:0 bits depends on the
WGM01:0 bit setting. Table 45 shows the COM01:0 bit functionality when the WGM01:0
bits are set to a normal or CTC mode (non-PWM).
Table 45. Compare Output Mode, non-PWM Mode
COM01
COM00 Description
0
0
Normal port operation, OC0 disconnected.
0
1
Toggle OC0 on Compare Match.
1
0
Clear OC0 on Compare Match.
1
1
Set OC0 on Compare Match.
Table 46 shows the COM01:0 bit functionality when the WGM01:0 bits are set to fast
PWM mode.
Table 46. Compare Output Mode, Fast PWM Mode⁽¹⁾
COM01
COM00 Description
0
0
Normal port operation, OC0 disconnected.
0
1
Reserved
1
0
Clear OC0 on Compare Match, set OC0 at TOP.
1
1
Set OC0 on Compare Match, clear OC0 at TOP.
Note:
1. A special case occurs when OCR0 equals TOP and COM01 is set. In this case, the
Compare Match is ignored, but the set or clear is done at TOP. See “Fast PWM
Mode” on page 85 for more details.
Table 47 shows the COM01:0 bit functionality when the WGM01:0 bits are set to phase
correct PWM mode.
Table 47. Compare Output Mode, Phase Correct PWM Mode⁽¹⁾
COM01
COM00 Description
0
0
Normal port operation, OC0 disconnected.
0
1
Reserved
1
0
Clear OC0 on Compare Match when up-counting. Set OC0 on
Compare Match when downcounting.
1
1
Set OC0 on Compare Match when up-counting. Clear OC0 on
Compare Match when downcounting.
Note:
1. A special case occurs when OCR0 equals TOP and COM01 is set. In this case, the
Compare Match is ignored, but the set or clear is done at TOP. See “Phase Correct
PWM Mode” on page 87 for more details.
• Bit 2:0 – CS02:0: Clock Select
The three Clock Select bits select the clock source to be used by the Timer/Counter.
Table 48. Clock Select Bit Description
CS02 CS01 CS00 Description
0
0
0
No clock source (Timer/counter stopped).
0
0
1
clk_I/O/(No prescaling)
0
1
0
clk_I/O/8 (From prescaler)
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