ATmega16A Atmel Corporation, ATmega16A Datasheet - Page 37

• Manufacturer Part Number: ATmega16A
• Manufacturer: Atmel Corporation

Specifications of ATmega16A

• Flash (kbytes): 16 Kbytes
• Pin Count: 44
• Max. Operating Frequency: 16 MHz
• Cpu: 8-bit AVR
• # Of Touch Channels: 16
• Hardware Qtouch Acquisition: No
• Max I/o Pins: 32
• Ext Interrupts: 3
• Usb Speed: No
• Usb Interface: No
• Spi: 1
• Twi (i2c): 1
• Uart: 1
• Graphic Lcd: No
• Video Decoder: No
• Camera Interface: No
• Adc Channels: 8
• Adc Resolution (bits): 10
• Adc Speed (ksps): 15
• Analog Comparators: 1
• Resistive Touch Screen: No
• Temp. Sensor: No
• Crypto Engine: No
• Sram (kbytes): 1
• Eeprom (bytes): 512
• Self Program Memory: YES
• Dram Memory: No
• Nand Interface: No
• Picopower: No
• Temp. Range (deg C): -40 to 85
• I/o Supply Class: 2.7 to 5.5
• Operating Voltage (vcc): 2.7 to 5.5
• Fpu: No
• Mpu / Mmu: no / no
• Timers: 3
• Output Compare Channels: 4
• Input Capture Channels: 1
• Pwm Channels: 4
• 32khz Rtc: Yes
• Calibrated Rc Oscillator: Yes

10. System Control and Reset
10.1
10.1.1
8154B–AVR–07/09
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.
reset circuitry.
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 ATmega16A has five sources of reset:
• Power-on Reset. The MCU is reset when the supply voltage is below the Power-on Reset
• External Reset. The MCU is reset when a low level is present on the RESET pin for longer
• Watchdog Reset. The MCU is reset when the Watchdog Timer period expires and the
• Brown-out Reset. The MCU is reset when the supply voltage V
• JTAG AVR Reset. The MCU is reset as long as there is a logic one in the Reset Register, one
threshold (V
than the minimum pulse length.
Watchdog is enabled.
Reset threshold (V
of the scan chains of the JTAG system. Refer to the section
scan” on page 232
“System and Reset Characteristics” on page 296
POT
).
BOT
for details.
) and the Brown-out Detector is enabled.
“Clock Sources” on page
defines the electrical parameters of the
“IEEE 1149.1 (JTAG) Boundary-
CC
Figure 10-1
25.
is below the Brown-out
ATmega16A
shows the reset
37