ATmega8HVA Atmel Corporation, ATmega8HVA Datasheet - Page 41

• Manufacturer Part Number: ATmega8HVA
• Manufacturer: Atmel Corporation

Specifications of ATmega8HVA

• Flash (kbytes): 8 Kbytes
• Pin Count: 28
• Max. Operating Frequency: 4 MHz
• Cpu: 8-bit AVR
• # Of Touch Channels: 3
• Hardware Qtouch Acquisition: No
• Max I/o Pins: 6
• Ext Interrupts: 3
• Usb Speed: No
• Usb Interface: No
• Spi: 1
• Graphic Lcd: No
• Video Decoder: No
• Camera Interface: No
• Adc Channels: 6
• Adc Resolution (bits): 12
• Adc Speed (ksps): 1.9
• Resistive Touch Screen: No
• Temp. Sensor: Yes
• Crypto Engine: No
• Sram (kbytes): 0.5
• Eeprom (bytes): 256
• Self Program Memory: YES
• Dram Memory: No
• Nand Interface: No
• Picopower: No
• Temp. Range (deg C): -20 to 85
• I/o Supply Class: 1.8 to 9.0
• Operating Voltage (vcc): 1.8 to 9.0
• Fpu: No
• Mpu / Mmu: no / no
• Timers: 2
• Output Compare Channels: 4
• Input Capture Channels: 2
• 32khz Rtc: No
• Calibrated Rc Oscillator: Yes

11. System Control and Reset
11.1
11.2
8024A–AVR–04/08
Resetting the AVR
Reset Sources
During reset, all I/O Registers are set to their initial values, and the program starts execution
from the Reset Vector. The instruction placed at the Reset Vector must be a JMP – Absolute
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
page 54
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 voltage regulator to reach a stable level before normal operation starts.
The time-out period of the delay counter is defined by the user through the SUT Fuses. The dif-
ferent selections for the delay period are presented in
The ATmega8HVA/16HVA has five sources of reset:
• The Power-on Reset module generates a Power-on Reset when the Voltage Regulator starts
• External Reset. The MCU is reset when a low level is present on the RESET pin for longer than
• Watchdog Reset. The MCU is reset when the Watchdog Timer period expires and the
• Brown-out Reset. The MCU is reset when V
• debugWIRE Reset. In On-chip Debug mode, the debugWIRE resets the MCU when giving the
up.
the minimum pulse length.
Watchdog is enabled.
See “Brown-out Detection” on page 44.
Reset command.
defines the electrical parameters of the reset circuitry.
”Reset Logic” on page 42
REG
is below the Brown-out Reset Threshold, V
”Clock Sources” on page
ATmega8HVA/16HVA
shows the reset logic.
25.
Table 12-2 on
BOT
41
.