Rainbow-electronics ATtiny2313 Manual do Utilizador descarregar pdf (Página 38)

ATtiny2313

2543A–AVR–08/03

Watchdog Reset When the Watchdog times out, it will generate a short reset pulse of one CK cycle dura-

tion. On the falling edge of this pulse, the delay timer starts counting the Time-out period

TOUT

. Refer to page 45 for details on operation of the Watchdog Timer.

Figure 19. Watchdog Reset During Operation

MCU Status Register –

MCUSR

The MCU Status Register provides information on which reset source caused an MCU

reset.

• Bit 3 – WDRF: Watchdog Reset Flag

This bit is set if a Watchdog Reset occurs. The bit is reset by a Power-on Reset, or by

writing a logic zero to the flag.

• Bit 2 – BORF: Brown-out Reset Flag

This bit is set if a Brown-out Reset occurs. The bit is reset by a Power-on Reset, or by

writing a logic zero to the flag.

• Bit 1 – EXTRF: External Reset Flag

This bit is set if an External Reset occurs. The bit is reset by a Power-on Reset, or by

writing a logic zero to the flag.

• Bit 0 – PORF: Power-on Reset Flag

This bit is set if a Power-on Reset occurs. The bit is reset only by writing a logic zero to

the flag.

To make use of the Reset flags to identify a reset condition, the user should read and

then reset the MCUSR as early as possible in the program. If the register is cleared

before another reset occurs, the source of the reset can be found by examining the reset

flags.

Bit 76543210

– – – – WDRF BORF EXTRF PORF MCUSR

Read/Write R R R R R/W R/W R/W R/W

Initial Value 0 0 0 See Bit Description

1 2 ... 33 34 35 36 37 38 39 40 41 42 43 ... 210 211

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Rainbow-electronics ATtiny2313 Manual do Utilizador Página 38