ATmega32U4 Atmel Corporation, ATmega32U4 Datasheet - Page 14

• 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

4.11
4.12
5. Security
14
Request From Host
Answer from Bootloader
Important note:
The bootloader performs a watchdog reset to generate the “hardware reset” that allows to exe-
cute the application section. After a watchdog reset occurs, the AVR watchdog is still running,
thus the application should take care to disable watchdog at program start-up (otherwise the
application that does not manage the hardware watchdog will run in an infinite reset loop).
No answer is returned by the device.
When the USB bootloader connection is initiated, the bootloader automatically enters a
read/write software security mode (independent of the product lock bits settings). This allows to
protect the on-chip flash content from read/write access over the USB interface. Thus the only
DFU command allowed after a USB bootloader connection is a “Full Chip Erase” command.
After this “Full Chip Erase” has been received and properly executed, all DFU commands are
allowed, and thus the on-chip flash can be reprogrammed and verified.
Id_write_command
04h
Command Identifier
data[0]
SETUP
IN
OUT
SETUP
03h
data[1]
00h
01h
data[2]
Jump O
DFU_UPLOAD
ZLP
DFU_UPLOAD
address
ption (3 or 5 Bytes)
data[3]
data[4]
Hardware reset
LJMP address
Description
7618C–AVR–07/08