ATMEGA8515-16AI(2010) View Datasheet(PDF) - Atmel Corporation

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Description

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ATMEGA8515-16AI
(Rev.:2010)

8-bit Microcontroller with 8K Bytes In-System Programmable Flash

Atmel Corporation 

Watchdog Reset

ATmega8515(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 53 for details on operation of the Watchdog Timer.

Figure 27. Watchdog Reset During Operation

CC

CK

MCU Control and Status

Register – MCUCSR

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

caused an MCU Reset.

Bit

7

6

5

4

3

2

1

0

–

–

SM2

–

WDRF BORF EXTRF PORF MCUCSR

Read/Write

R/W

R/W

R

R/W

R/W

R/W

R/W

R/W

Initial Value

0

0

0

See Bit Description

• 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 MCUCSR 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.

49

2512K–AVR–01/10

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