ATmega32U4 Atmel Corporation, ATmega32U4 Datasheet - Page 257

• 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

21.6
21.6.1
21.6.2
21.6.3
7766F–AVR–11/10
General Operating Modes
Introduction
Power-on and reset
Interrupts
The USB controller is disabled and reset after an hardware reset generated by:
But another available and optional CPU reset source is:
In this case, the USB controller is reset, but not disabled (so that the device remains attached).
The next diagram explains the USB controller main states on power-on:
Figure 21-7. USB controller states after reset
USB Controller state after an hardware reset is ‘Reset’. In this state:
After setting USBE, the USB Controller enters the Device state. The controller is ‘Idle’.
The USB Controller can at any time be stopped by clearing USBE. In fact, clearing USBE acts
as an hardware reset.
Two interrupts vectors are assigned to USB interface.
• USBE is not set
• the USB controller clock is stopped in order to minimize the power consumption
• the USB controller is disabled,
• the USB pad is in the suspend mode,
• the Device USB controller internal state is reset.
(FRZCLK=1),
– Power on reset
– External reset
– Watchdog reset
– Brown out reset
– JTAG reset
– USB End Of Reset
Clock stopped
Dev ice
FRZCLK=1
Macro off
USBE=1
USBE=0
Reset
USBE=0
RESET
HW
USBE=0
<any other
state>
ATmega16/32U4
257