AT91SAM9260B-CU-999 Atmel, AT91SAM9260B-CU-999 Datasheet - Page 47

• Manufacturer Part Number: AT91SAM9260B-CU-999
• Description: IC MCU ARM9 217LFBGA
• Manufacturer: Atmel
• Series: AT91SAMr

Specifications of AT91SAM9260B-CU-999

• Core Processor: ARM9
• Core Size: 16/32-Bit
• Speed: 180MHz
• Connectivity: EBI/EMI, Ethernet, I²C, MMC, SPI, SSC, UART/USART, USB
• Peripherals: POR, WDT
• Number Of I /o: 96
• Program Memory Size: 32KB (32K x 8)
• Program Memory Type: ROM
• Ram Size: 24K x 8
• Voltage - Supply (vcc/vdd): 1.65 V ~ 1.95 V
• Data Converters: A/D 4x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 217-LFBGA
• Processor Series: AT91SAMx
• Core: ARM926EJ-S
• Data Bus Width: 32 bit
• Data Ram Size: 8 KB
• Interface Type: 2-Wire, EBI, I2S, SPI, USART
• Maximum Clock Frequency: 180 MHz
• Number Of Programmable I/os: 96
• Number Of Timers: 6
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• 3rd Party Development Tools: JTRACE-ARM-2M, MDK-ARM, RL-ARM, ULINK2
• Development Tools By Supplier: AT91SAM-ICE, AT91-ISP, AT91SAM9260-EK
• Minimum Operating Temperature: - 40 C
• On-chip Adc: 10 bit, 4 Channel
• For Use With: AT91SAM9260-EK - KIT EVAL FOR AT91SAM9260AT91SAM-ICE - EMULATOR FOR AT91 ARM7/ARM9
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Eeprom Size: -
• Lead Free Status / Rohs Status: Details

10.7.2.2
10.8
10.8.1
6221I–ATARM–17-Jul-09
Write-though Operation
Write-back Operation
Bus Interface Unit
Supported Transfers
Write Buffer
The DCache contains an eight data word entry, single address entry write-back buffer used to
hold write-back data for cache line eviction or cleaning of dirty cache lines.
The Write Buffer can hold up to 16 words of data and four separate addresses. DCache and
Write Buffer operations are closely connected as their configuration is set in each section by the
page descriptor in the MMU translation table.
The ARM926EJ-S contains a write buffer that has a 16-word data buffer and a four- address buf-
fer. The write buffer is used for all writes to a bufferable region, write-through region and write-
back region. It also allows to avoid stalling the processor when writes to external memory are
performed. When a store occurs, data is written to the write buffer at core speed (high speed).
The write buffer then completes the store to external memory at bus speed (typically slower than
the core speed). During this time, the ARM9EJ-S processor can preform other tasks.
DCache and Write Buffer support write-back and write-through memory regions, controlled by C
and B bits in each section and page descriptor within the MMU translation tables.
When a cache write hit occurs, the DCache line is updated. The updated data is then written to
the write buffer which transfers it to external memory.
When a cache write miss occurs, a line, chosen by round robin or another algorithm, is stored in
the write buffer which transfers it to external memory.
When a cache write hit occurs, the cache line or half line is marked as dirty, meaning that its
contents are not up-to-date with those in the external memory.
When a cache write miss occurs, a line, chosen by round robin or another algorithm, is stored in
the write buffer which transfers it to external memory.
The ARM926EJ-S features a Bus Interface Unit (BIU) that arbitrates and schedules AHB
requests. The BIU implements a multi-layer AHB, based on the AHB-Lite protocol, that enables
parallel access paths between multiple AHB masters and slaves in a system. This is achieved by
using a more complex interconnection matrix and gives the benefit of increased overall bus
bandwidth, and a more flexible system architecture.
The multi-master bus architecture has a number of benefits:
The ARM926EJ-S processor performs all AHB accesses as single word, bursts of four words, or
bursts of eight words. Any ARM9EJ-S core request that is not 1, 4, 8 words in size is split into
• It allows the development of multi-master systems with an increased bus bandwidth and a
• Each AHB layer becomes simple because it only has one master, so no arbitration or master-
• The arbitration becomes effective when more than one master wants to access the same
flexible architecture.
to-slave muxing is required. AHB layers, implementing AHB-Lite protocol, do not have to
support request and grant, nor do they have to support retry and split transactions.
slave simultaneously.
AT91SAM9260
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