ATmega16U2 Atmel Corporation, ATmega16U2 Datasheet - Page 198

• 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

21.4
21.5
21.6
7799D–AVR–11/10
USB reset
Endpoint selection
Endpoint activation
The data toggle field remains unchanged.
The other registers remain unchanged.
The endpoint configuration remains active and the endpoint is still enabled.
The endpoint reset may be associated with a clear of the data toggle command (RSTDT bit) as
an answer to the CLEAR_FEATURE USB command.
When an USB reset is detected on the USB line (SEO state with a minimal duration of 100µs),
the next operations are performed by the controller:
If the hardware reset function is selected, a reset is generated to the CPU core without disabling
the USB controller (that remains in the same state than after a USB Reset).
Prior to any operation performed by the CPU, the endpoint must first be selected. This is done
by setting the EPNUM[2:0] bits (in UENUM register) with the endpoint number which will be
managed by the CPU.
The CPU can then access to the various endpoint registers and data.
The endpoint is maintained under reset as long as the EPEN bit is not set.
The following flow must be respected in order to activate an endpoint:
• the Rx and Tx banks are cleared and their internal pointers are restored,
• the UEINTX, UESTA0X and UESTA1X are restored to their reset value.
• All the endpoints are disabled.
• The default control endpoint remains configured.
• The data toggle of the default control endpoint is cleared.
ATmega8U2/16U2/32U2
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