Datasheet

170
ATmega16U4/32U4 [DATASHEET]
Atmel-7766J-USB-ATmega16U4/32U4-Datasheet_04/2016
The table shows the COM4D1:0 bit functionality when the PWM4D and WGM40 bits are set to Phase and
Frequency Correct PWM Mode
• Bit 1 - FOC4D: Force Output Compare Match 4D
The FOC4D bit is only active when the PWM4D bit specify a non-PWM mode.
Writing a logical one to this bit forces a change in the Waveform Output (OCW4D) and the Output Compare pin
(OC4D) according to the values already set in COM4D1 and COM4D0. If COM4D1 and COM4D0 written in the
same cycle as FOC4D, the new settings will be used. The Force Output Compare bit can be used to change the
output pin value regardless of the timer value. The automatic action programmed in COM4D1 and COM4D0
takes place as if a compare match had occurred, but no interrupt is generated. The FOC4D bit is always read as
zero.
• Bit 0 - PWM4D: Pulse Width Modulator D Enable
When set (one) this bit enables PWM mode based on comparator OCR4D.
15.12.4 TCCR4D – Timer/Counter4 Control Register D
• Bit 7 - FPIE4: Fault Protection Interrupt Enable
Setting this bit (to one) enables the Fault Protection Interrupt.
• Bit 6– FPEN4: Fault Protection Mode Enable
Setting this bit (to one) activates the Fault Protection Mode.
• Bit 5 – FPNC4: Fault Protection Noise Canceler
Setting this bit activates the Fault Protection Noise Canceler. When the noise canceler is activated, the input
from the Fault Protection Pin (INT0) is filtered. The filter function requires four successive equal valued samples
of the INT0 pin for changing its output. The Fault Protection is therefore delayed by four Oscillator cycles when
the noise canceler is enabled.
• Bit 4 – FPES4: Fault Protection Edge Select
This bit selects which edge on the Fault Protection pin (INT0) is used to trigger a fault event. When the FPES4
bit is written to zero, a falling (negative) edge is used as trigger, and when the FPES4 bit is written to one, a
rising (positive) edge will trigger the fault.
Table 15-17. Compare Output Mode, Phase and Frequency Correct PWM Mode
COM4D1..0 OCW4D Behavior OC4D Pin OC4D 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
Bit 76543210
FPIE4 FPEN4 FPNC4 FPES4 FPAC4 FPF4 WGM41 WGM40 TCCR4D
Read/Write R/W R/W R/W R/W R/W R/W R/W R/W
Initial value 00000000