The ATmega8A 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 longer than the minimum pulse length.
- 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 is below the Brown-out Reset threshold (VBOT) and the Brown-out Detector is enabled.
Figure 1. Reset Logic
