ATmega32U4 Atmel Corporation, ATmega32U4 Datasheet - Page 55

• Manufacturer Part Number: ATmega32U4
• Manufacturer: Atmel Corporation

Specifications of ATmega32U4

• Flash (kbytes): 32 Kbytes
• Pin Count: 44
• Max. Operating Frequency: 16 MHz
• Cpu: 8-bit AVR
• # Of Touch Channels: 14
• Hardware Qtouch Acquisition: No
• Max I/o Pins: 26
• Ext Interrupts: 13
• Usb Transceiver: 1
• Usb Speed: Full Speed
• Usb Interface: Device
• Spi: 2
• Twi (i2c): 1
• Uart: 1
• Graphic Lcd: No
• Video Decoder: No
• Camera Interface: No
• Adc Channels: 12
• Adc Resolution (bits): 10
• Adc Speed (ksps): 15
• Analog Comparators: 1
• Resistive Touch Screen: No
• Temp. Sensor: Yes
• Crypto Engine: No
• Sram (kbytes): 3.3
• Eeprom (bytes): 1024
• 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: 4
• Output Compare Channels: 12
• Input Capture Channels: 2
• Pwm Channels: 8
• 32khz Rtc: No
• Calibrated Rc Oscillator: Yes

8.2
7766F–AVR–11/10
Watchdog Timer
ADC is used. To reduce power consumption in Power-down mode, the user can avoid the three
conditions above to ensure that the reference is turned off before entering Power-down mode.
Table 8-4.
Note:
ATmega16U4/ATmega32U4 has an Enhanced Watchdog Timer (WDT). The main features are:
•
•
•
•
Figure 8-8.
The Watchdog Timer (WDT) is a timer counting cycles of a separate on-chip 128 kHz oscillator.
The WDT gives an interrupt or a system reset when the counter reaches a given time-out value.
In normal operation mode, it is required that the system uses the WDR - Watchdog Timer Reset
- instruction to restart the counter before the time-out value is reached. If the system doesn't
restart the counter, an interrupt or system reset will be issued.
In Interrupt mode, the WDT gives an interrupt when the timer expires. This interrupt can be used
to wake the device from sleep-modes, and also as a general system timer. One example is to
limit the maximum time allowed for certain operations, giving an interrupt when the operation
has run longer than expected. In System Reset mode, the WDT gives a reset when the timer
Symbol
Clocked from separate On-chip Oscillator
3 Operating modes
Selectable Time-out period from 16ms to 8s
Possible Hardware fuse Watchdog always on (WDTON) for fail-safe mode
V
t
I
– Interrupt
– System Reset
– Interrupt and System Reset
BG
BG
BG
1. Values are guidelines only. Actual values are TBD.
Parameter
Bandgap reference voltage
Bandgap reference start-up time
Bandgap reference current
consumption
WATCHDOG
RESET
Internal Voltage Reference Characteristics
Watchdog Timer
OSCILLATOR
128kHz
WDIE
WDIF
WDE
Condition
TBD
TBD
TBD
(1)
TBD
Min
ATmega16/32U4
Typ
1.1
40
10
WDP0
WDP1
WDP2
WDP3
MCU RESET
INTERRUPT
Max
TBD
TBD
70
Units
µA
µs
V
55