ATMEGA8L-8AC Atmel, ATMEGA8L-8AC Datasheet - Page 37

• Manufacturer Part Number: ATMEGA8L-8AC
• Description: IC AVR MCU 8K LV 8MHZ COM 32TQFP
• Manufacturer: Atmel
• Series: AVR® ATmegar

Specifications of ATMEGA8L-8AC

• Core Processor: AVR
• Core Size: 8-Bit
• Speed: 8MHz
• Connectivity: I²C, SPI, UART/USART
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Number Of I /o: 23
• Program Memory Size: 8KB (4K x 16)
• Program Memory Type: FLASH
• Eeprom Size: 512 x 8
• Ram Size: 1K x 8
• Voltage - Supply (vcc/vdd): 2.7 V ~ 5.5 V
• Data Converters: A/D 8x10b
• Oscillator Type: Internal
• Operating Temperature: 0°C ~ 70°C
• Package / Case: 32-TQFP, 32-VQFP
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Other names: ATMEGA8L8AC

System Control
and Reset
Resetting the AVR
Reset Sources
2486Z–AVR–02/11
During Reset, all I/O Registers are set to their initial values, and the program starts execution
from the Reset Vector. If the program never enables an interrupt source, the Interrupt Vectors
are not used, and regular program code can be placed at these locations. This is also the case if
the Reset Vector is in the Application section while the Interrupt Vectors are in the boot section
or vice versa. The circuit diagram in
page 38
The I/O ports of the AVR are immediately reset to their initial state when a reset source goes
active. This does not require any clock source to be running.
After all reset sources have gone inactive, a delay counter is invoked, stretching the internal
reset. This allows the power to reach a stable level before normal operation starts. The time-out
period of the delay counter is defined by the user through the CKSEL Fuses. The different selec-
tions for the delay period are presented in
The ATmega8 has four sources of Reset:
•
•
•
•
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 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 V
Reset threshold (V
defines the electrical parameters of the reset circuitry.
POT
)
BOT
) and the Brown-out Detector is enabled
Figure 14 on page 38
“Clock Sources” on page
shows the Reset Logic.
CC
26.
is below the Brown-out
ATmega8(L)
Table 15 on
37