Datasheet
163
7766F–AVR–11/10
ATmega16/32U4
Table 15-8 shows the COM4A1:0 bit functionality when the PWM4A, WGM40 and WGM41 bits
are set to Phase and Frequency Correct PWM Mode.
Table 15-9 shows the COM4A1:0 bit functionality when the PWM4A, WGM40 and WGM41 bits
are set to single-slope PWM6 Mode. In the PWM6 Mode the same Waveform Output (OCW4A)
is used for generating all waveforms and the Output Compare values OC4A and OC4A
are con-
nected on OC4x and OC4x
pins as described below.
Table 15-10 shows the COM4A1:0 bit functionality when the PWM4A, WGM40 and WGM41 bits
are set to dual-slope PWM6 Mode.I
• Bits 5,4 - COM4B1, COM4B0: Comparator B Output Mode, Bits 1 and 0
These bits control the behavior of the Waveform Output (OCW4B) and the connection of the
Output Compare pin (OC4B). If one or both of the COM4B1:0 bits are set, the OC4B output
overrides the normal port functionality of the I/O pin it is connected to. The complementary
OC4B
output is connected only in PWM modes when the COM4B1:0 bits are set to “01”. Note
Table 15-8. Compare Output Mode, Phase and Frequency Correct PWM Mode
COM1A1..0 OCW1A Behavior OC4A Pin OC4A Pin
00 Normal port operation. Disconnected Disconnected
01
Cleared on Compare Match when up-counting.
Set on Compare Match when down-counting.
Connected Connected
10
Cleared on Compare Match when up-counting.
Set on Compare Match when down-counting.
Connected Disconnected
11
Set on Compare Match when up-counting.
Cleared on Compare Match when down-counting.
Connected Disconnected
Table 15-9. Compare Output Mode, Single-Slope PWM6 Mode
COM4A1..0 OCW4A Behavior OC4x Pin OC4x Pin
00 Normal port operation. Disconnected Disconnected
01
Cleared on Compare Match.
Set when TCNT4 = 0x000.
OC4A OC4A
10
Cleared on Compare Match.
Set when TCNT4 = 0x000.
OC4A OC4A
11
Set on Compare Match.
Cleared when TCNT4 = 0x000.
OC4A OC4A
Table 15-10. Compare Output Mode, Dual-Slope PWM6 Mode
COM4A1..0 OCW4A Behavior OC4x Pin OC4x Pin
00 Normal port operation. Disconnected Disconnected
01
Cleared on Compare Match when up-counting.
Set on Compare Match when down-counting.
OC4A OC4A
10
Cleared on Compare Match when up-counting.
Set on Compare Match when down-counting.
OC4A OC4A
11
Set on Compare Match when up-counting.
Cleared on Compare Match when down-counting.
OC4A OC4A