Datasheet

171
ATmega16U4/32U4 [DATASHEET]
Atmel-7766J-USB-ATmega16U4/32U4-Datasheet_04/2016
• Bit 3 - FPAC4: Fault Protection Analog Comparator Enable
When written logic one, this bit enables the Fault Protection function in Timer/Counter4 to be triggered by the
Analog Comparator. The comparator output is in this case directly connected to the Fault Protection front-end
logic, making the comparator utilize the noise canceler and edge select features of the Timer/Counter4 Fault
Protection interrupt. When written logic zero, no connection between the Analog Comparator and the Fault
Protection function exists. To make the comparator trigger the Timer/Counter4 Fault Protection interrupt, the
FPIE4 bit in the Timer/Counter4 Control Register D (TCCR4D) must be set.
• Bit 2- FPF4: Fault Protection Interrupt Flag
When the FPIE4 bit is set (one), the Fault Protection Interrupt is enabled. Activity on the pin will cause an
interrupt request even, if the Fault Protection pin is configured as an output. The corresponding interrupt of Fault
Protection Interrupt Request is executed from the Fault Protection Interrupt Vector. The bit FPF4 is cleared by
hardware when executing the corresponding interrupt handling vector. Alternatively, FPF4 is cleared after a
synchronization clock cycle by writing a logical one to the flag. When the SREG I-bit, FPIE4 and FPF4 are set,
the Fault Interrupt is executed.
• Bits 1:0 - WGM41, WGM40: Waveform Generation Mode Bits
This bit associated with the PWM4x bits control the counting sequence of the counter, the source for type of
waveform generation to be used, see the table below.
The Modes of operation supported by the Timer/Counter4 are: Normal mode (counter), Fast PWM Mode, Phase
and Frequency Correct PWM and PWM6 Modes.
15.12.5 TCCR4E – Timer/Counter4 Control Register E
• Bit 7 - TLOCK4: Register Update Lock
This bit controls the Compare registers update. When this bit is set, writing to the Compare registers will not
affect the output, however the values are stored and will be updated to the Compare registers when the
TLOCK4 bit will be cleared.
Refer to “Synchronous update” on page 151 for more details.
Table 15-18. Waveform Generation Mode Bit Description
PWM4x WGM41..40 Timer/Counter Mode of Operation TOP
Update of
OCR4x at
TOV4 Flag
Set on
0 xx Normal OCR4C Immediate TOP
1 00 Fast PWM OCR4C TOP TOP
1 01 Phase and Frequency Correct PWM OCR4C BOTTOM BOTTOM
1 10 PWM6 / Single-slope OCR4C TOP TOP
1 11 PWM6 / Dual-slope OCR4C BOTTOM BOTTOM
Bit 76543210
TLOCK4 ENHC4 OC4OE5 OC4OE4 OC4OE3 OC4OE2 OC4OE1 OC4OE0 TCCR4E
Read/Write R R R/W R/W R/W R/W R/W R/W
Initial value 00000000