ATMEGA161-8PC View Datasheet(PDF) - Atmel Corporation

Part Name

Description

MFG CO.

ATMEGA161-8PC

8-bit Microcontroller with 16K Bytes of In-System Programmable Flash

Atmel Corporation 

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Reset Sources

The ATmega161 has four sources of reset:

• Power-on Reset. The MCU is reset when the supply voltage is below the power-on reset threshold (VPOT).

• External Reset. The MCU is reset when a low level is present on the RESET pin for more than 500 ns.

• Watchdog Reset. The MCU is reset when the Watchdog timer period expires and the Watchdog is enabled.

• Brown-out Reset. The MCU is reset when the supply voltage VCC falls below a certain voltage.

During reset, all I/O registers are then set to their initial values, and the program starts execution from address $000. The

instruction placed in address $000 must be an JMP – relative jump – instruction to the reset handling routine. If the program

never enables an interrupt source, the interrupt vectors are not used, and regular program code can be placed at these

locations. The circuit diagram in Figure 24 shows the reset logic. Table 3 and Table 4 defines the timing and electrical

parameters of the reset circuitry

Figure 24. Reset Logic

DATA BUS

MCU Status

Register (MCUSR)

BODEN

BODLEVEL

Brown-Out

Reset Circuit

CKSEL[2:0]

Delay Counters

Full

CK

24

ATmega161(L)

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