ATmega16U2 Atmel Corporation, ATmega16U2 Datasheet - Page 197

• Manufacturer Part Number: ATmega16U2
• Manufacturer: Atmel Corporation

Specifications of ATmega16U2

• Flash (kbytes): 16 Kbytes
• Pin Count: 32
• Max. Operating Frequency: 16 MHz
• Cpu: 8-bit AVR
• # Of Touch Channels: 12
• Hardware Qtouch Acquisition: No
• Max I/o Pins: 22
• Ext Interrupts: 21
• Usb Transceiver: 1
• Usb Speed: Full Speed
• Usb Interface: Device
• Spi: 2
• Uart: 1
• Graphic Lcd: No
• Video Decoder: No
• Camera Interface: No
• Analog Comparators: 1
• Resistive Touch Screen: No
• Temp. Sensor: No
• Crypto Engine: No
• Sram (kbytes): 0.5
• 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: 2
• Output Compare Channels: 5
• Input Capture Channels: 1
• Pwm Channels: 4
• 32khz Rtc: No
• Calibrated Rc Oscillator: Yes

21. USB Device Operating modes
21.1
21.2
21.3
7799D–AVR–11/10
Overview
Power-on and reset
Endpoint reset
The USB device controller supports full speed data transfers. In addition to the default control
endpoint, it provides four other endpoints, which can be configured in control, bulk, interrupt or
isochronous modes:
The controller starts in the “idle” mode. In this mode, the pad consumption is reduced to the
minimum.
The next diagram explains the USB device controller main states on power-on:
Figure 21-1. USB device controller states after reset
The reset state of the Device controller is:
The D+ pull-up will be activated as soon as the DETACH bit is cleared.
The macro is in the ‘Idle’ state after reset with a minimum power consumption and does not
need to have the PLL activated to enter in this state.
The USB device controller can at any time be reset by clearing USBE.
An endpoint can be reset at any time by setting in the UERST register the bit corresponding to
the endpoint (EPRSTx). This resets:
• the macro clock is stopped in order to minimize the power consumption (FRZCLK set),
• the USB device controller internal state is reset (all the registers are reset to their default
• the endpoint banks are reset
• the D+ pull up are not activated (mode Detach)
• the internal state machine on that endpoint,
• Endpoint 0:
• Endpoint 1 and 2:
• Endpoint 3 and 4:
value. Note that DETACH is set.)
Programmable size FIFO up to 64 bytes, default control endpoint
Programmable size FIFO up to 64 bytes.
Programmable size FIFO up to 64 bytes with ping-pong mode.
RESET
HW
USBE=0
Reset
USBE=0
state>
<any
other
USBE=1
UID=1
ATmega8U2/16U2/32U2
Idle
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