ATmega32U4 Atmel Corporation, ATmega32U4 Datasheet - Page 335

• 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

27.5.3
7766F–AVR–11/10
External Hardware conditions
is programmed, the Reset Vector will always point to the Boot Loader Reset and the fuse can
only be changed through the serial or parallel programming interface.
Table 27-4.
Note:
The Hardware Boot Enable Fuse (HWBE) can be programmed (See
special hardware conditions under reset, the bootloader execution is forced after reset.
Table 27-5.
Note:
When the HWBE fuse is enable the ALE/HWB pin is configured as input during reset and sam-
pled during reset rising edge. When ALE/HWB pin is ‘0’ during reset rising edge, the reset vector
will be set as the Boot Loader Reset address and the Boot Loader will be executed (See Figures
27-3).
Figure 27-3. Boot Process Description
BOOTRST
HWBE
1
0
1
0
1. “1” means unprogrammed, “0” means programmed
1. “1” means unprogrammed, “0” means programmed
Boot Reset Fuse
Hardware Boot Enable Fuse
Reset Address
Reset Vector = Application Reset (address 0x0000)
Reset Vector = Boot Loader Reset (see
Reset Address
ALE/HWB pin can not be used to force Boot Loader execution after reset
ALE/HWB pin is used during reset to force bootloader execution after reset
Reset Vector = Application Reset
BOOTRST ?
HWBE
?
(1)
(1)
ALE/HWB
RESET
Table 27-8 on page
Ext. Hardware
Conditions ?
Reset Vector =Boot Lhoader Reset
ATmega16/32U4
t
SHRH
Table
344)
27-5) so that upon
t
HHRH
335