atmega161-4pi ATMEL Corporation, atmega161-4pi Datasheet - Page 25

• Manufacturer Part Number: atmega161-4pi
• Description: 8-bit Microcontroller With 16k Bytes Of In-system Programmable Flash
• Manufacturer: ATMEL Corporation

Reset Sources
1228D–AVR–02/07
The ATmega161 has three sources of Reset:
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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 a 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 define the timing and electrical parameters of the reset circuitry.
Figure 24. Reset Logic
Power-on Reset. The MCU is reset when the supply voltage is below the Power-on
Reset threshold (V
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.
POT
).
CK
Register (MCUSR)
MCU Status
DATA BUS
CKSEL[2:0]
Delay Counters
ATmega161(L)
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