ATmega16 Atmel Corporation, ATmega16 Datasheet - Page 37

• Manufacturer Part Number: ATmega16
• Manufacturer: Atmel Corporation

Specifications of ATmega16

• 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

System Control
and Reset
Resetting the AVR
Reset Sources
2466T–AVR–07/10
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 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 ATmega16 has five 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
(V
JTAG AVR Reset.
The MCU is reset as long as there is a logic one in the Reset Register, one of the scan
chains of the JTAG system. Refer to the section
page 228
Table 15
BOT
) and the Brown-out Detector is enabled.
for details.
defines the electrical parameters of the reset circuitry.
“Clock Sources” on page
CC
is below the Brown-out Reset threshold
“IEEE 1149.1 (JTAG) Boundary-scan” on
25.
Figure 15
ATmega16(L)
shows the reset
POT
).
37