ATmega16U4 datasheet(158/408 Pages) ATMEL

158 / 408 page

158

7766D–AVR–01/09

ATmega16U4/ATmega32U4

Figure 15-18. Timer/Counter Timing Diagram, Setting of OCF1x, with Prescaler (f

clkT4/8)

Figure 15-19. Timer/Counter Timing Diagram, with Prescaler (f

clkT4/8)

15.10 Fault Protection Unit

The Timer/Counter4 incorporates a Fault Protection unit that can disable the PWM output pins, if

an external event is triggered. The external signal indicating an event can be applied via the

external interrupt INT0 pin or alternatively, via the analog-comparator unit. The Fault Protection

unit is illustrated by the block diagram shown in Figure 15-20. The elements of the block diagram

that are not directly a part of the Fault Protection unit are gray shaded.

Figure 15-20. Fault Protection Unit Block Diagram

When the Fault Protection mode is enabled by the Fault Protection Enable (FPEN4) bit and a

change of the logic level (an event) occurs on the external interrupt pin (INT0), alternatively on

the Analog Comparator output (ACO), and this change confirms to the setting of the edge detec-

tor, a Fault Protection mode will be triggered. When a Fault Protection is triggered, the COM4x

bits are cleared, Output Comparators are disconnected from the PWM output pins and the

PORTB register bits are connected on the PWM output pins. The Fault Protection Enable

(FPEN4) is automatically cleared at the same system clock as the COM4nx bits are cleared. If

the Fault Protection Interrupt Enable bit (FPIE4) is set, a Fault Protection interrupt is generated

and the FPEN4 bit is cleared. Alternatively the FPEN4 bit can be polled by software to figure out

when the Timer/Counter has entered to Fault Protection mode.

OCFnx

OCRnx

TCNTn

OCRnx Value

OCRnx - 1

OCRnx

OCRnx + 1

OCRnx + 2

clk

PCK

clk

(clk

PCK /8)

TOVn

TCNTn

BOTTOM + 1

BOTTOM

BOTTOM + 1

clk

PCK

clk

(clk

PCK /8)

Analog

Comparator

Noise

Canceler

INT0

Edge

Detector

FPAC4

FPNC4

FPES4

ACO*

FPEN4

Timer/Counter4

FAULT_PROTECTION (Int. Req.)

ATmega16U4 Datasheet(PDF) 158 Page - ATMEL Corporation

ATmega16U4 Datasheet(HTML) 158 Page - ATMEL Corporation

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

Datasheet Download

Link URL