ATmega406 Atmel Corporation, ATmega406 Datasheet - Page 39

• Manufacturer Part Number: ATmega406
• Manufacturer: Atmel Corporation

Specifications of ATmega406

• Flash (kbytes): 40 Kbytes
• Pin Count: 48
• Max. Operating Frequency: 1 MHz
• Cpu: 8-bit AVR
• # Of Touch Channels: 8
• Hardware Qtouch Acquisition: No
• Max I/o Pins: 18
• Ext Interrupts: 4
• Usb Speed: No
• Usb Interface: No
• Twi (i2c): 1
• Graphic Lcd: No
• Video Decoder: No
• Camera Interface: No
• Adc Channels: 11
• Adc Resolution (bits): 12
• Adc Speed (ksps): 1.9
• Resistive Touch Screen: No
• Temp. Sensor: Yes
• Crypto Engine: No
• Sram (kbytes): 2
• Eeprom (bytes): 512
• Self Program Memory: YES
• Dram Memory: No
• Nand Interface: No
• Picopower: No
• Temp. Range (deg C): -30 to 85
• I/o Supply Class: 4.0 to 25
• Operating Voltage (vcc): 4.0 to 25
• Fpu: No
• Mpu / Mmu: no / no
• Timers: 2
• Output Compare Channels: 3
• Pwm Channels: 2
• 32khz Rtc: Yes
• Calibrated Rc Oscillator: Yes

9. System Control and Reset
9.1
9.2
2548E–AVR–07/06
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. 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
logic.
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 ATmega406 has several reset sources:
• Power-on Reset. If the chip is in Power-off mode, the Charger Detect module generates a reset
• 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 VREG is below the Brown-out Reset Threshold,
• JTAG AVR Reset. The MCU is Reset as long as there is a logic one in the Reset Register, one
pulse when a charger is connected.See
for details.
the minimum pulse length. See
Watchdog is enabled. See
V
of the scan chains of the JTAG system. See
page 171
BOT
. See
for details.
”Brown-out Detection” on page 42
”Watchdog Reset” on page 42
”External Reset” on page 41
”Power-on Reset and Charger Connect” on page 40
”JTAG Interface and On-chip Debug System” on
for details.
”Clock Sources” on page
for details.
for details.
Figure 9-1
ATmega406
26.
shows the reset
39