ATMEGA64-16MI View Datasheet(PDF) - Atmel Corporation

Part Name

Description

Manufacturer

ATMEGA64-16MI

8-bit AVR® Microcontroller with 64K Bytes In-System Programmable Flash

Atmel Corporation 

Watchdog Reset

ATmega64(L)

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

tTOUT. Refer to page 54 for details on operation of the Watchdog Timer.

Figure 27. Watchdog Reset During Operation

CC

CK

MCU Control and Status

Register – MCUCSR(1)

The MCU Control and Status Register provides information on which reset source

caused an MCU Reset.

Bit

7

6

JTD

–

Read/Write

R/W

R

Initial Value

0

0

5

4

3

2

1

0

–

JTRF WDRF BORF EXTRF PORF MCUCSR

R

R/W

R/W

R/W

R/W

R/W

0

See Bit Description

Note: 1. Only EXTRF and PORF are available in mega103 compatibility mode.

• Bit 4 – JTRF: JTAG Reset Flag

This bit is set if a reset is being caused by a logic one in the JTAG Reset Register

selected by the JTAG instruction AVR_RESET. This bit is reset by a Brown-out Reset,

or by writing a logic zero to the flag.

• 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.

53

2490G–AVR–03/04

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