AT32UC3A4128 Atmel Corporation, AT32UC3A4128 Datasheet - Page 64
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AT32UC3A4128
Manufacturer Part Number
AT32UC3A4128
Description
Manufacturer
Atmel Corporation
Datasheets
1.AT32UC3A0128.pdf
(377 pages)
2.AT32UC3A0128.pdf
(33 pages)
3.AT32UC3A0128.pdf
(159 pages)
4.AT32UC3A3128.pdf
(91 pages)
5.AT32UC3A3128.pdf
(1012 pages)
Specifications of AT32UC3A4128
Flash (kbytes)
128 Kbytes
Pin Count
100
Max. Operating Frequency
66 MHz
Cpu
32-bit AVR
Hardware Qtouch Acquisition
No
Usb Transceiver
1
Usb Speed
Hi-Speed
Usb Interface
Device + OTG
Spi
6
Twi (i2c)
2
Uart
4
Sd / Emmc
2
Graphic Lcd
No
Video Decoder
No
Camera Interface
No
Adc Channels
8
Adc Resolution (bits)
10
Resistive Touch Screen
No
Temp. Sensor
No
Crypto Engine
No
Sram (kbytes)
128
Self Program Memory
YES
Dram Memory
No
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
6
Input Capture Channels
6
32khz Rtc
Yes
Calibrated Rc Oscillator
Yes
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6.5
6.6
6.6.1
6.6.2
32002F–03/2010
IRAM Write buffer
Memory barriers
Instruction memory barriers
Data memory barriers
being performed. Refer to the device datasheet for information on any relationships between
CPU and device clock frequencies imposed by the local bus.
The EX stage has a write buffer used to hold data to be written to the IRAM section. The opera-
tion of this buffer is usually transparent to the programmer. The programmer should be aware of
the following:
Memory barriers are constructs used to enfore memory consitency. Caches and self-modifying
code may cause memory to become inconsistent. AVR32UC has a simple pipeline with no
caches, so there is usually no need for memory barriers. Mechanisms for memory barriers are
present to handle the cases where such barriers are needed.
An instruction memory barrier (IMB) is usually only needed when executing self-modifying code,
for example when self-programming program flash. In this case, one must ensure that all levels
in the memory hierarchy are consistent. Due to the simple non-cached memory system in
AVR32UC, this is usually trivial.
The programmer should make sure that an IMB is used if there is a possibility that an instruction
to be modified by self-modifying code has already been prefetched by the instruction prefetch
unit. In this case, an IMB should be inserted between the instruction modifying the code and the
execution of the modified instruction. To make sure that the modified version of the instruction is
executed, the prefetch buffer should be flushed between changing the program memory and
executing the new version of the program.
Any instruction performing a change-of flow, such as return from exception, conditional
branches, unconditional branches, subprogram call or return, or instructions writing to PC would
implement an IMB in AVR32UC.
A data memory barrier (DMB) is used to make sure that a data memory access, either a read or
write, is actually performed before the rest of the code is executed. Caches, write buffers and
• The IRAM has a single port, allowing either one read or one write per clock cycle.
• The write buffer is pipelined, allowing sequential writes to IRAM to be pipelined without any
• Any read instruction to IRAM in EX will be performed immediately, even if a previous store
• If a read instruction in EX accesses the same address as the data in the write buffer is to be
• The contents of the write buffer is written to the physical RAM as soon as the memory
• The state of the write buffer may affect the timing of RMW instructions, see
pipeline stalls. The previous contents of the write buffer is written to the RAM in parallel with
the new store data being placed in the write buffer.
instruction has placed data to store in the write buffer. In this case, the previous store data
remains in the write buffer and will be written back to RAM in a later clock cycle.
stored to, the pipeline is stalled for one clock cycle while the write buffer is emptied to RAM.
The read will be performed normally in the next clock cycle.
interface is not used by any instructions.
write instructions” on page 84
for details
“Read-modify-
AVR32
64