ATmega32U2 Atmel Corporation, ATmega32U2 Datasheet - Page 189

• Manufacturer Part Number: ATmega32U2
• Manufacturer: Atmel Corporation

Specifications of ATmega32U2

• Flash (kbytes): 32 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: 20
• 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): 1
• 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: 2
• Output Compare Channels: 5
• Input Capture Channels: 1
• Pwm Channels: 4
• 32khz Rtc: No
• Calibrated Rc Oscillator: Yes

20.3.3
20.4
20.4.1
20.4.2
7799D–AVR–11/10
General Operating Modes
Design guidelines
Introduction
Power-on and reset
The following design guidelines should be met:
In addition it is highly recommended to connect a 10µF capacitor to the VBUS line
The USB controller is disabled and reset after a hardware reset generated by:
In the case of USB End Of Reset (EOR), the USB controller is reset, but not disabled. Therefore
the device remains attached.
Figure 20-7 on page 189
Figure 20-7. USB controller states after reset
• Serial resistors on USB Data lines must have 22 Ohms value (
• Traces from the input USB receptacle (or from the cable connection in the case of a tethered
• Voltage transient / ESD suppressors may also be used to prevent USB pads to be damaged
• U
device) to the USB microcontroller pads should be as short as possible, and follow differential
traces routing rules (same length, as near as possible and avoid vias accumulation).
by external disturbances.
cap
– Power on reset
– External reset
– Watchdog reset
– Brown out reset
– debugWIRE reset
– USB End Of Reset
capacitor should be 1µF (
Clock stopped
FRZCLK = 1
(macro off)
USBE = 1
Device
illustrates the USB controller main states on power-on:
+/-
10%) for correct operation.
USBE = 0
Reset
HW RESET
(from EOR)
ATmega8U2/16U2/32U2
USBE = 0
USBE = 0
+/-
(except from EOR)
Any other
5%).
HW RESET
state
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