ATmega32U4 Atmel Corporation, ATmega32U4 Datasheet - Page 15

• 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

6. Accessing the Low level Flash Drivers
7618C–AVR–07/08
The AT90USB USB bootloader is located in the boot section of the on-chip flash memory, mean-
while the bootloader section is the unique memory location allowed to execute on-chip flash
memory write operations (SPM instruction is decoded only in this section).
Thus applications which require on-chip flash write access can perform calls to specific entry
points located in the USB bootloader.
The USB bootloader provides several Application Programming Interfaces (API) that allows the
application to access low level flash drivers located in the boot section. These APIs allow the fol-
lowing operations:
Figure 6-1.
• Page Erase
• Page Write
• Load word in the temporary page buffer
USB bootloader API calls
Application section
Boot section
Low level flash drivers
USB Bootloader
API entry points
Low Level
Flash Operations
Target Page modified
On-Chip flash Request:
Application
"Page Erase"
"Page Write"
"Load Word"
15