AT32UC3A3128 Atmel Corporation, AT32UC3A3128 Datasheet - Page 37

• Manufacturer Part Number: AT32UC3A3128
• Manufacturer: Atmel Corporation

Specifications of AT32UC3A3128

• Flash (kbytes): 128 Kbytes
• Pin Count: 144
• Max. Operating Frequency: 66 MHz
• Cpu: 32-bit AVR
• # Of Touch Channels: 32
• Hardware Qtouch Acquisition: No
• Max I/o Pins: 110
• Ext Interrupts: 110
• Usb Transceiver: 1
• Usb Speed: Hi-Speed
• Usb Interface: Device + OTG
• Spi: 6
• Twi (i2c): 2
• Uart: 4
• Lin: 4
• Ssc: 1
• Sd / Emmc: 1
• Graphic Lcd: No
• Video Decoder: No
• Camera Interface: No
• Adc Channels: 8
• Adc Resolution (bits): 10
• Adc Speed (ksps): 384
• Resistive Touch Screen: No
• Dac Channels: 2
• Dac Resolution (bits): 16
• Temp. Sensor: No
• Crypto Engine: No
• Sram (kbytes): 128
• Self Program Memory: YES
• External Bus Interface: 1
• Dram Memory: sdram
• Nand Interface: Yes
• Picopower: No
• Temp. Range (deg C): -40 to 85
• I/o Supply Class: 3.0 to 3.6
• Operating Voltage (vcc): 3.0 to 3.6
• Fpu: No
• Mpu / Mmu: Yes / No
• Timers: 6
• Output Compare Channels: 18
• Input Capture Channels: 12
• Pwm Channels: 12
• 32khz Rtc: Yes
• Calibrated Rc Oscillator: Yes

5.2
32000D–04/2011
Understanding the MMU
Figure 5-2.
The AVR32 Memory Management Unit (MMU) is responsible for mapping virtual to physical
addresses. When a memory access is performed, the MMU translates the virtual address speci-
fied into a physical address, while checking the access permissions. If an error occurs in the
translation process, or Operating System intervention is needed for some reason, the MMU will
issue an exception, allowing the problem to be resolved by software.
The MMU architecture uses paging to map memory pages from the 32-bit virtual address space
to a 32-bit physical address space. Page sizes of 1, 4, 64 kilobytes and 1 megabyte are sup-
ported. Each page has individual access rights, providing fine protection granularity.
The information needed in order to perform the virtual-to-physical mapping resides in a page
table. Each page has its own entry in the page table. The page table also contains protection
information and other data needed in the translation process. Conceptually, the page table is
accessed for every memory access, in order to read the mapping information for each page.
In order to speed up the translation process, a special page table cache is used. This cache is
called a Translation Lookaside Buffer (TLB). The TLB contains the n most recently used page
table entries. The number n of entries in the TLB is IMPLEMENTATION DEFINED. It is also
IMPLEMENTATION DEFINED whether a single unified TLB should be used for both instruction
and memory accesses, or if two separate TLBs are implemented. The architecture supports one
or two TLBs with up to 64 entries in each. TLB entries can also be locked in the TLB, guarantee-
ing high-speed memory accesses.
0xFFFFFFFF
0xC0000000
0xE0000000
0xA0000000
0x80000000
0x00000000
P0 / U0
P4
P3
P2
P1
The AVR32 segment translation map
512MB translated space,
512MB system space,
512MB non-translated
512MB non-translated
space, non-cacheable
Virtual address space
2GB translated space
space, cacheable
non-cacheable
cacheable
cacheable
translation
Segment
Physical address space
512MB physical address
2GB physical address
space
space
0xFFFFFFFF
0xE0000000
0x80000000
0x20000000
0x00000000
AVR32
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